Physics SPM Paper 2 Tips - 89 MODIFICATION and 11 DECISION MAKING ( Question and Answer)

MODIFICATION-SECTION B Soalan ini berada di dalam Section B. Cadangan dan alasan dalam soalan ini juga boleh digunakan di dalam Soalan Section C – Making Decision. Dengan contoh yang diberikan ini akan berupaya meningkatkan kemahiran berfikir pelajar di dalam membuat modifikasi dan membuat keputusan bagi situasi yang diberikan di dalam soalan peperiksaan.Insyaallah. CHAPTER 1

1. Suitable ruler to use in laboratory Suggestion Smallest size scale 0.1 cm High accuracy High consistency Plastic material Thin thickness

Explanation More accurate Less error in measurement Low relative deviations Avoid parallax error Avoid parallax error

CHAPTER 2 2. Explain the suitability feature of arm exercise equipment. Suggestion Spring made of steel Two // more spring arrange in parallel Spring with ticker wire Smaller diameter coil of spring Choose large force constant spring

Explanation Can withstand higher force The spring system is stiffer Wire will not easily break The smaller the diameter coil less elastic the spring, so the arm exercise would not so hard Will make strong spring, the spring will stiffer and not broken easily

3. Suggest the suitable cloth , equipment and techniques to improve high jumper athlete suggestion Use tight and light suit Use spikes shoes Use thicker mattress The athlete have to sprint before jump Athlete have to bend the body during fall and their safety .

Explanation Less air fraction Better grip support while running and prevent slippery Increase time impact , reduce impulsive force . prevent back injury Can increase kinetic energy Increase the time impact , reduce impulsive force

4. Explain the characteristic of spring to make baby’s cradle. Suggestion Choose large force constant spring Choose large diameter of wire Large diameter coil of spring The spring is made of steel or alloy The arrangement of spring is two or more line in parallel

Explanation Will make strong spring, the spring will stiffer and not broken easily. The larger diameter the stiffer the spring is. The larger the diameter coil more elastic the spring is Steel and alloy is stiffer than iron The spring is stiffer

5. Explain the most suitable design of spring for shock absorber for motorcycles. Suggestion Small diameter of spring coil Choose large diameter of wire Force constant is more than 1000N Higher spring constant Small natural frequency

Explanation Enough space for the spring The larger the diameter the stiffer the spring Can support motorcyclist and passenger up to 100kg Small compression of the spring To reduce bumping, comfortable for user

6. Explain the simple characteristic of the rocket than can travel with greater acceleration. Suggestions Choose metal with high strength and hardness Frame of rocket is made of low density metal Multistage rocket invented

Rocket need to carry a tank of oxygen Silver color rocket Cover the body of rocket with heat insulator Aerodynamic shape

Explanations Even under pressure the shape will not change easily Lighter, can increase acceleration Each stage has burning fuel, pump and combustion chamber. It will slip off when fuel of each chamber completely burn. When the mass decreases, the acceleration increase To enable the combustion of fuel in space Reflect light efficiently so the temperature of the rocket will not rise Friction between air and body will increase heat. The insulator will reduce heat conductivity Reduce air friction, move faster

7. Suggest and explain the build of water bottle rocket in school competition to move higher altitude and has longer time on the air. Suggestions The body of rocket must be tough Smaller mass The shape is streamline/aerodynamic Nose cone or bullet shape on top of body 45 angle of launching The volume of water is half or 1/3 from the whole volume Attach 3 or 4 fins at the tail of rocket space equally Attach parachute

Explanations Do not break easily in high pressure and when landing Rocket will accelerate faster Reduce air resistance To improve the aerodynamic of rocket The rocket can travel maximum distance To increase momentum and impulsive force Rocket will move smooth and stable will make the rocket floating and has longer time on the air before landing//decrease the speed of falling due to air resistance

8. Give suggestion to improve the design of jet engine so that it can be use for larger airplane at the higher speed. Suggestions Increase more fuel injectors Increase the size of the combustion chamber Decrease the diameter of the nozzle Increase the speed of blade/use bigger blade Blade and engine made of strong materials

Explanations More fuel to be burnt to produce greater force More space for fuel to burnt Exhaust gas ejected at higher velocity Increase the air intake Can withstand strong pressure and won’t break easily

9. Base on the physic principle, suggest the design of roller skate track so it can be use to oscillate skate continuously. Suggestions Semi circular curve shape Smooth surface The slope slightly increase and decrease Use strong material such concrete of foundation of the track Soft layer at the surface

Explanations Exchange between kinetic energy and gravitational potential easily Reduce frictional force/easy to slide Easy to oscillates cause by changing of energy Withstand high impact such as high force of jumping and landing Reduce impulsive force when landing, low risk if

accident 10. Explain the most suitable design of motorcycle that can move fast, safe and save time in racing. Suggestions Lower seat height Bigger width of tire Less thread pattern Smaller mass With ABS

Explanations Lower center of gravity or more stable or safer to turn. Bigger surface area, better support or low pressure acts on the tires or more friction when breaks. To decrease friction of tires to the road, can move fast Lighter, can move faster or low inertia Motorcycle does not stop immediately or can be controlled if direction changes or does not move sideways or more friction with ABS

11. Suggest and explain how to make suitable beach motorcycle which able to move on the sand smoothly and comfortable. Suggestions Deep thread patter // more definitive pattern Large tire (big surface contact with ground) Soft seat and water resistance Excellent resistance to rusting Attach shock absorber with higher spring constant and small natural frequency. Low density body

Explanations Better grip on sand, able to move smoothly on sand Reduce total pressure of car, increase stability and the car would not get stuck in the sand Comfortable for cycles and would not get wet easily Everlasting. Would not rust easily Reduce bumping, comfortable to cycle with Lighter, would not stuck in sand

12.

Suggest the suitable cloth and the best techniques to catch ball to prevent injury for goalkeeper. Suggestion Wear glove Use soft material for glove Wear cloth which is made from material with moderate specific heat capacity Base of shoes has stud When catching the ball, the goal keeper should move his hand backwards The ball should have enough air pressure inside

Explanations Reduce painful of the player’s hands when touching the ball with big impulsive force. Lengthen the time impact, reduce impulsive force. The cloth can absorb more heat when the player is sweating to maintain the temperature of player. Player give great pressure to make stud sink into ground and give stronger support without slipping. This action lengthen the time impact between ball and hand, so it reduce the impulsive force. Shorter the time impact between foot and ball, so impulsive force increase then the ball will has high speed and travel far away.

13. Using physics concept, suggest and explain suitable athlete’s attires, running, jumping, landing techniques and other aspects to help the long jumper can jump further. Suggestion Use tight and light suit Use spike shoes The athlete have to sprint before jump The athlete have to push the body infront while jumping Athlete have to bent the body during fall 14. Safety feature in car

Explanation Less air friction Better grip support while running and prevent slippery Can increase the kinetic energy//momentum Increase the elastic potential energy//able to increase longer distance of jumping Increase the time impact, reduce impulsive force, less injured

Characteristic The bumper of car is prone to crash The sitting space of the passenger is reinforced Use safety belt Use air bag Antilock breaking system(ABS) Strong steel struts Tire with tread

Explanation It will increase the time impact, the impulsive force will reduce To protect the passenger During collision, safety belt will hold the passengers from thrown infront due to inertia Will inflate when accident occurs, the driver safe from hitting steering Allow car to stop quickly on slippery road and prevent from skidding Give good protection from side on collision Can stays contact with road, prever slippery

15. Explain the suitable loaded lorry which can carry liquid, such as petrol Suggestion The load of lorry should be divided into many smaller tank The load must be tied Far gap distances between tractor and trailer Use more tire for lorry Small belt behind lorry Use antilock break system (ABS)

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Explanation To reduce effect of inertia So it will no fall of from the lorry Prevent collision between tractor and trailer, easier when turning Pressure will be separate to all tires, able to carry more loads. Lower pressure better support and stability To discharge spark, safety reason to prevent from burning the petrol The lorry can stop easily without skidding

Explain the design of and how kayak which can travel faster and safer.

Suggestion Streamline /aerodynamic shape of body Smooth surface body /coated with wax Low density material Strong material body and peddle Wider peddle surface Wear safety jacket

Explanation Reduce water resistance Reduce friction of body towards water Lighter , easier to float, easy to carry and sail faster Everlasting , not easily broken Greater force because more water are peddled up Passenger can float and safe if they fall into water.

17. Give suggestion to design a sail boat which can travel faster and smooth. Suggestion Streamline /aerodynamic shape of board Smooth surface board/coated with wax Low density material Strong material Wider sail

Explanation Reduce water and air resistance,can increase lifting Reduce friction toward water Lighter, easier to float and sail faster Withstand strong wind, not easily damage Greater lifting force because more wind are captured

18.

Modified the ship that can carry more and heavier load, move faster and safe while travelling. Suggestion Strong material Low density material Has more than two stage,plimsoll line

Explanation Can withstand great force Light weight Safe to travel on the fresh and salt water

Big size Aerodynamic/streamline shape Waterproof sail

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Can place more goods Reduce water friction. Sail would not get e=wet easily.

Suggest how to increase the safety for motorbike racer to reduce injuries /

accident Suggestion Use helmet Use helmet with hard outer casing and soft inner liner Use safety jacket Use gloves Use padded leathers suit

Explanation To protect the head Helmet reduce head injuries in a crash by spreading the impact with hard outer casing and absorb energy with soft inner linear of styrofoam To protect the from injuries , cut ,burn To protect the hand Will soften any impact and protect the skin from abrasion

20.

An earth-monitoring satellite falls into the earth’s atmosphere at a high velocity and reaches a high temperature. This is caused by the earth’s gravitational force and air resistance.Using the appropriate physics concepts, suggest and explain suitable designs or ways to protect the satellite and its equipment: Suggestion Aerodynamic shape Heat shield / material that is hard to burn High melting point //ceramic Landing in water // air bag Light material / / small mass // low density Paracute / /Retro rocket Hard material // stiff composite

Explanation To reduce air resistance To protect the capsule Do not melt Increase time of impact// Reduce impulsive force -Reduce the inertia // -reduce the momentum // -reduce impuls To reduce speed Not easy to bend

21.

Explain how you would design the pile driving system.[the ram hammer is lifted to a height by the crane and allowed to fall on the pile. Modification Large hammer weight Ram hammer made from hard material such as alloys Hammer raised at higher position Stronger End of the top of the concrete pile Sharp End of the bottom of the concrete pile

Reason Large momentum when it hit the pile Not break easily/last longer Inrease the gravitational potential energy To avoid break at the top couse by the hammer To increase the pressure

CHAPTER 3

22.

Efficient brake system

Suggestions Type of liquid: oil Thickness of brake line :high The ratio of cross sectional area for wheel piston and master piston :high

Explanations Uncompressible To counter the high pressure from the liquid To produce larger force on wheel piston

The chosen of type of brake for front rear wheel: Front wheel - disc Rear wheel - drum

Disc brake is more efficient than drum brake

23. Explain the design of hydrometer which can be use to determine a wide range of densities of liquid. Suggestions Small stem and long Glass wall Large diameter of bulb Scale can be made bigger or smaller than the density of water.[calibration] - The hydrometer is floated in alcohol. The liquid level at the stem is marked (upper level) - Then, the hydrometer is floated in higher density liquid like mercury and marked (lower level) Lead shots

Explanations Increase sensitivity where the scale division are far apart so that small changes in density can be detected Do not erode and small adhesive force High up thrust / displaces more liquid / able to float easily Ability to measure a wide range of densities of liquids.

Hydrometer can stay upright

24. Describe the suitable design to build mobile tent for Sure Heboh event which will be construct at open space for a week. Using appropriate physics concept, suggests and explain. Suggestion Choose low density metal for frame Use hollow rod which can assemble easily Water proof canvas Anti rust rod Sharp end rod

Explanation Light weight and strong Hollow rod is not heavy, but equally strong, easy to mobile anywhere, faster to build, can reduce the cost of construction and transport If raining, would not getting wet Can withstand rain and long lasting Small surface area, so higher pressure to ground, yet the tent can be planted into ground firmly and stand still

25. Explain the necessary modification for the structure of dentist chair for children that are suitable and save for the adult. Suggestion Increase the cross-sectional area of big piston and decrease the cross-sectional area of small piston The wall of pipe is made up of strong alloy to hold the fluid Change the less control into electric touch control The surface area of the seat enlarged Use non-corrosive oil in jack

Explanation To increase the output force acting on big piston / to lift havier adult / to increase force multiplier of system To withstand the strong pressure that might cause cracking in the channel To lift or lowered the chair to the desire weight more easily and safety To support the people with the large bodies So that the wall of the pipe will not be controlled and cause leakage

26. Explain the build and design of hot air ballon wich can fly higher altitude faster and suggest some safety aspect. Suggestion Large ballon

Explanation Produce bigger buoyant / upthrust force, increase the volume of air displacement

Many hot air burner Synthetic nylon ballon Gas temperature is high Total of mass is low Rattan basket Fly on early morning or late afternoon

Heat up the gas inside faster Air proof, light weight and strong material Reduce the density of air in ballon Ballon move upward faster Longer the time impact, reduce the impulsive force to passanger when landing The temperature outside the ballon is cooler compare to the inside of ballon, so the ballon will rise higher

27.

Explain the basic structure of small submarine that can be use for underwater exploration. Suggestion Strong material Aerodynamic shape Thick wall High density materials Ballast tank Sonar transmitter and receiver

Explanation Does not break easily Reduce water resistance Water pressure increase with depth Increase mass / can submerge easily To increase or reduce weight To estimate and depth

28. Suggest the design of submarine which can submerge and float in the sea. Suggestion Ballast tank are partially filled with water Aerodynamic // streamline body Use hard and stiff materials for body Attach periscope Use nuclear power sources to generate power

Explanation The submarine will partially float To reduce water resistance To overcome the pressure of water in the sea To view surrounding area when submarine float Cheap and lasting power

29. Explain the characteristic of material to be use for making the sole of jungle trekking shoes. Suggestion Rubber sole Low density Many stud Low expansion effect Excellent ability of stretch

Explanation Good impact absorber Light weight Give extra grip Not loose easily Comfortable to feet, foot can move unstressed

30. Using physics concept, explain necessary deep sea diving suit and other accessory to carry. Suggestion Choose strong helmet with thick metal and glass to cover head

Explanation To withstand high pressure of water and protect the head

Use thick glass in front of diver face

Enable the diver to see surrounding and at the same time able to withstand the pressureof water

Use water proof suit and able to withstand pressure

Due to depth, the pressure under water is very high

Bring along gas containing mixture of oxygen Use very heavy suit

To provide oxygen to diver for breath The diver enable to stand on the floor of ocean and able to fight buoyancy of water

31. Modified the passanger airplane to cargo airplane that needs to carry more laod, less use of fuel, effenciency and safety to travel.

Suggestion Increase the size of the body Increase the length of the wing Increase the thickness of the body Use a more powerful engine Increase the number of tyres Protective bar between the cabin and the pilot Pilot has ejected seat during emergency

Explanation To increase the space To increase the upthrust To stand higher pressure difference To overcome bigger inertia and do more work per unit time To support higher mass or pressure while landing To prevent moving object to knock at the pilot while landing To save the pilot if plane crash happened

32. Design Vacuum Cleaner Suggestion Large fan driven Powerfull of lectric motor Narrower inlet opening Using a very large filter to block dust particles while allowing air moleculs to pass through Larger spaced for depositing and collecting the dust particles

Explanation Inrease the spped and amaunt of airflows Inrease the spped and amaunt of airflows Inrease the velocity/decrease air pressure To have a lots of surface area and many pores for air to flow through Ensure that the air flows through the filter is not block by too many dust particles

33. Design paint sprayer Suggestion Large size of air vessel Rubber material for the vessel Narrow shape of the tube Fibre glass material for the rod Size of nozzle is narrow at the end

Explanation Compress more air/can exert large pressure More elastic/easier to squeeze Air can move with high speed Stronger and last longer The paint can be sprayed evenly

34. Design hidraulic jack Suggestion Bigger crossectional area of slave piston(big piston) Small crossectional area of master piston(small piston) Longer handle Low density of a body Oil for liquid Release valve between small and main reservoir(reset)

Explanation Produced higher force Less forced is needed/produced bigger pressurre Less forced is needed to press small piston(master piston) Lighter Non-compressable Liquid can flows into small reservoir easily when push the reset button.

35. Design hydrometer Suggestion Bulb with lead shot at the lower section Cylinder with bigger diameter at the bottom Cylinder with smaller diameter at the upper section Smaller scale Filled with air Glass wall CHAPTER 4

Explanation To submerge the hydrometer and not overturn not overturn/increase stability A small reading scale can be incorporated/inrease the sensitivity inrease the sensitivity Inrease the beyoncy force Not corrode easily

36. Most suitable design of thermometer to use in Antarctica Suggestion Use alcohol as liquid – in glass thermometer Use thin wall of bulb Use small diameter of capillary tube Use thick glass wall Use round glass stem

Explanation Freezing point of alcohol is -115oC .So , it will not freeze at low temperature So it will sensitive to the change of heat Alcohol can expand at high rate for the small change in temperature The loss of heat to surrounding is small Can act as magnifying glass , so the alcohol level can be seen clearer

37. Most suitable design of clinical thermometer Suggestion Use mercury The scale range from 35oC to 42oC Small diameter of capillary tube// extra fine bore tube Use thin glass wall of bulb Use round glass stem and wall

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Explanation Easy to read because it colour and opaque To measure human body heat Mercury can expand at high rate for a small change in temperature Sensitive to change of temperature Can act as ,magnifying glass. So, mercury can be seen clearly

Explain the design and the characteristics of the cooking pan

Suggestion Base is made of a copper High density of base Body is made of aluminium Handle is made of wood or plastic Choose low density material for handle Transparent pot cover

Explanation Copper has a lower heat capacity it become hot very quickly Heavier base make the pot stable and not topple over easily Low specific heat capacity becomes hot very quickly but it low density make it overall weight of weight lighter High specific heat capacity so the handle do not become hot . Safe Does not add much to the total weight of pot Able to cooker to see the food. Food cover will trap the heat

39. Suggest and explian the design of water heater to boil a large quantity of water faster ,efficient and safely Suggestion Use tungsten Coiled High melting point Lower rate of rusting Use thermostat

Explanation High melting point,high heat energy Longer wire,increase the resistance Not easy to melt at high temperature Does not get rust easily When temperatures reach 100 Celsius, the water heater will automatically turn off

40. Determine the modification to be made for container,so the cut fruit will keep cool, remain fresh and easily seen by customers. Suggestion Use container with high specific heat capacity Place small ice packet below the bottom of the cut friuts Add salt to the packet of ice

Explanation Able to slow down the loss of heat from the container The cut fruits is chill and juicy, ice able to absorb a large amount of latent heat when melt Foreign matter will increase the freezing point of ice, so this will slow down the ice from melting

White wall colour of container The container has double wall Transparent wall of container in front of customer

Can avoid absorbtion of heat from the surrounding Avoid heat from surrounding transferred easily to container. The inside container remains cool The customer can see and choose the cut fruits easily

41. Investigate the most suitable liquid that can be use as coolant for car engine using physics concept. Suggestion Low freezing point liquid High boiling point liquid High specific heat capacity liquid Low ability to react with metal

Explanation Will not freeze easily during winter weather Do not easily boil when absorbing heat from the engine Can transfer large contain of heat with a small rise in temperature. Able to cool up the engine The metal part of the engine will not corrode easily

42. Most suitable thermometer for laboratory to measure the temperature of ice and boiling point of water Suggestion Size of the bulb is small Use thin wall of bulb Use mercury

Use thin wall capillary Has minimum size scale with small division

Explanation Does not need a lot of heat to heat up the mercury to expand So it is sensitive to change of heat Freeezing point of the mercury is -39 degree celsius and boling point 357 degree celsius . Able to has a range from -10 to 110 degree Celsius. Mercury can expand a high rate for small change of temperature Able quick heat transfer from the surrounding to the mercury. So, the thermemeter is more sensitive Making thermometer a sensitive instrument

43. Modified and explain the design of an efficient solar water-heating system on the roof. Suggestion Pipe embedded in plate must be long Use metal pipe as pipe inside the plate Use insulator behind the absorber panel Use black absorber panel Cover the top of the panel with glass Put the tank at higher level

Explanation Longer pipe will has greater surface area which can absorb heat faster Metal is good heat conductor , so heat will easily transmit to water Insulator will prevent the heat loss Black is good heat absorber Heat will trap inside due to green house effect To give higher pressure

44. Explain the build of solar cooker oven that been use in science month competition at your school to boil 500ml water in short time. Suggestion Build the solar cooker with shiny// silver colour reflector inside Use metal cooker Paint the outside part of the solar cooker and the cooker ( contain water ) with black colour Wrap the cooker with plastic or glass To trap heat, the temperataure will increase

Explanation The light will reflect to the cooker and heat up the water Good conductor To absorb Avoid heat from release to sorrounding To absorb heat, the water boil faster

45. Suggest the design of heating system in the house and characteristics of heating agent. The house use central heating system with boiler, radiator and pipelines. Suggestion Use strong material Use metal pipe with good heat conductor Increase length of cooling coil Use greater boiling point liquid Low rate of rusting material The bigger size of radiator fan Pipe in coil structure is used

Explanation Not easily break Increase the rate of heat transfer Can transfer the heat faster to surrounding Liquid not easily change into vapour Long lasting, not easily rust Can blow and cool down larger area Increase the time of floe and increase the quantity of haet transferred.

46. Suggest the characteristic of material to build food container which can keep the food warm. Suggestion Food container should made of low density material Melting point of container should be high Specific heat capacity should be high Thermal conductivity is low.i Double wall

47.

Explanation Lighter , the container able to be move from one place to another. To prevent the container from melting up when hot food is store inside So the container will not get hot easily. Safe to touch and handle. Good heat insulator , to ensure the heat not loss and the food remain hot. To prevent hest loss.

Explain the characteristic and design of thermos flasks to maintain hot water.

Suggestion Use hollow plastic stopper Vacuum space Has double wall Double walled tube coated with shiny paint Double walled made of glass

Explanation Able to trap air as air is poor heat conductor.so,less heat loss through stopper. Prevent heat loss through conduction or convection Has vacuum in between heat not easier pass through the wall of thermos. Shiny surface reflect heat from the wall of thermos flasks back to water.so the water remain hot. Glass is bad conductor.it will reduce heat loss.

48.

Explain how the design of radiator of the car and characteristic of cooling agent which can absorb heat at short time, Suggestion Increase the length/area of cooling coil Increase the number of fin blades Use larger fan Use cooling agent liquid with greater boiling point Use cooling agent liquid with higher specific heat capacity

Explanation Can transfer the heat faster to the surrounding Can cool down faster Can cool down larger area It won’t boild easily in high temperature Able to absorb large amount of heat

CHAPTER 5 49. Determine and explain in the build of magnifying glass to be use for enlarging the image of stamp Suggestion Choose convex lens Excellent clarity of lens Small focal length Medium diameter of lens

Explanation The image will magnify The image is clearer Able to focus nearer Able to be hold by hand to identify the stamps

The object is place less distance than focal length

The image form is magnify, virtual and upright

50. Explain the suitability of the mirror that be use in shop to watch over the customer Suggestion Use convex mirror Greater reflectivity of material Choose a bigger size of mirror Place the mirror at the corner of shop ceiling Low density

Explanation Wider field of view Clearer image Enable wider view and sharper image Easier to look at and won’t disturb the customer pathway Lighter to hang up

51. Design fibre optic Suggestion Use refractive index of outer layer is less than the refractive index of inner layer Use high flexibility material Use strong material Use thin material Low density material

Explanation So that total internal reflection can happen in the fiber optic. so that it can be bend easily do not break easily Lighter // can be use in small area Lighter

52. Determine and explain the build of microscope using lens P and Q with focal length of 15 cm and 5 cm respectively. Suggest modification that need to be done to get brighter ang bigger image. Suggestion P as eye piece and Q as objective lens Fo < u fo + fe Store in a cool and dry place Use more powerful// shorter focal length lenses Use a lamp near the object// use bigger diameter of objective lens

Explaination Focal length of P is longer than Q To produce real, inverted and magnified image To produce virtual. Inverted and bigger image// to acts as a magnifying glass To produce bigger image from the eyepiece // to increase the magnification To avoid formation fungus at the lenses To produce bigger image To produce brighter image

53. Explain the suitable characteristic of the mirror to be use as outdoor safety mirror at the corner of the road Suggestion Use convex mirror Excellent weather resistance Excellent impact resistance of material Bigger size mirror Greater reflectivity of material Place at the sharp road corner , at bending road Small roof

Explanation Wider field of view Able to withstand bad weather Save cost, everlasting To enable a wider view and sharper image Clearer image even in bad weather To minimize from accident occur, to enable motorist see the oncoming traffic Protect from rain drop for better image

54. Detemine and explain the build of Astro disc using appropriate physics concepts. Suggestion Choose convex curve parabolic All signal are focus on focal point Smooth surface of disc Locate the disc at high and facing towards

Explanation The signals come can be focus at one point Better reception Better reflection No obstacle, better signal

satellite Clean surface of disc, no water drop or dirt

Better reflection, almost 100% reception receive by feed horn

55. Modified the slide projector that need to be place in school hall and can be seen by many student with clearer image. suggestion Use higher power bulb The filament of the bulb is at the focus point of the concave mirror More curvature Lens between f and 2f Increase the distance or further away the screen Electric fan operates during and after the lamp is switches on Use condenser mirror Use a concave mirror instead of plane mirror Place the filament at centre of curvature of the converging mirror // use high powered lens Use heat filter

Explaination Higher intensity of light or more light produced The light focuses at one point. // parallel ray can be obtained after reflection by concave mirror More light to be reflected (upward) // less light toward other direction other than upward To produce real ang enlarge or bigger images Larger image produced Cooling system to stabilized the temperature (heat energy produced by filament bulb) to increase the projector lifetime To concentrate more light to the slide Focus the light directly to the lens // increase the intensity og light Light goes directly from the lamp and reflect back on the same path // increase the intensity of light toward the transparency // to get brighter image To absorb excess heat to the transparency

56. Determine and explain the build of telescope using lens J and K with lens K is thicker than lens J which produce bigger and clearer image. Suggestion • C hoose lens K as eyepiece lens Lens K is thicker than lens J

•

Choose lens J as objective lens Use bigger diameter lens as objective lens

Use low power convex lens as the objective lens Use high power convex lens as the eye lens Use bigger diameter of objective lens

CHAPTER 6 57. Design a good beach

Expalanation • Light ray is refracted more in lens K than lens J, focal length of lens K is shorter than lens J • Therefore the thickerthe lens, the greater the refraction of light and with that the shorter the focal length of a lens will be Characteristics of objective lens for telescope is • Has larger surface area which allow more light enter • Has a longer focal length • Magnification of telescope =f0/fe Low power lens has a longer focal length ,fo higher, magnification higher High power lens has a shorter focal length,fe higher, magnnification higher More light permitted to enter the telescope and a clearer image is seen

Suggestion near the bay High retaining walls

Wall from concrete Concrete barrier structure with a gap Tambak laut supaya lebih cetek More number of tree Uneven surface of retaining wall

Explanation divergence of the waves energy /calmer Over flow To reflect the waves from the shore Reduce direct impact of the waves on the shore reduce erosion are built Waves passing through the gap will be diffracted in the children’s area. -reduce amplitude Reduce speed Diffraction occur will reduce tha amplitude Reduce energy

58.

Suggest and explain how ordinary fishing boat can be upgrade to the new boat which complete equipment to detect the crowd of fish. Suggestion Attach radar system to the ship a) Ultrasonic transmitter a) Microfone reciever b) CRO Use ultrasonic wave Use high energy wave

Explanation This equipment needs to detect crowd of fish and for measurement the depth of the crowd of fish -Use to produce ultrasonic pulses To detect ultrasonic pulses -To measure the depth of fish by calculating d=vt/2; d=depth, v=velocity, t=time -Ultrasound not produce sound -Ultrasonic wave has higher frequency, more energy, so it can move further The penetrating power is higher

59. Explain the suitable design or method to build quality concert hall. Suggestion Cover the hard wall with soft board or thick curtain Place the wall with hole or egg carton design Fixed 2 loud speaker in concert hall Arranged the sit at antinodal place Use glass or mirror hall which is the type which are not easily broken Use special computer to generate sound wave which produce destructive inteference

Explanation Soft surface can absorb sound and reduce reflection of sound Can reduce reflection of sound so sound will be clearer/reduce echo Loud speaker can act as coherent sources for constructive inteference Strong sound can be heard Sound with high frequency might break the glass Audience can enjoy better presentation without disturbance

60. Explain the suitable design of retaining wall to protect the ship at the harbor Suggestion Build concrete retaining wall Retaining wall should be curved and uneven surface Build retaining wall in front of the bay Retaining wall has gap The gap at retaining wall is narrow( smaller than wave length) There are slope at the bottom of retaining wall Retaining wall should be build higher Build the jetty at bay

Explaination Can withstand impact of the wave, difficult to crack Prevent reflection of wave back to the ship The wave are calmer at thr region Diffraction will occur The greater the curvature of wavefront will occur. Amplitude after passing gap is smaller At shallow region, the wavelength of wave is smaller, so the velocity of the wave smaller To ensure no spill over of wave The wave at bay is calmer

61. Explain the characteristics of parabolic radar system to detect signal from satellite communication.

Suggestion Large diameter size of parabolic disc Type of wave transmited is Microwave The distance of the signal receiver from the centre of parabolic disc is the same as the focal length Place parabolic disc higher from the ground Place parabolic disc at clearplace

Explanation Able to receives more electric signal Has high frequency, high energy, short wavelength so it is easy to be reflected The signal can be focus to the centre of the parabolic disc The signal with not be block by trees or anything and the signal easy to be detected No signal disturbance

CHAPTER 7 62. Suggest the suitable lamp that can be use in the library, cheaper yet become the room brighter Suggestion Lamp with parallel circuit Attach shiny reflector Low power lamp High efficiency lamp // fluorescent Long life span lamp Low price lamp

Explanation If any lamp were burn out, others can still be used Can reflect light more, no need to install more lamp, the room will become brighter. Safe cost The room looks brighter No need to replace often Save money

63. Explain the modification of menthol bulb lamp to efficient lamp to be use in study room. Suggestion Use the fluorescent lamp not a filament bulb Bigger cover with white colour Use the adjustable stand or portable Connect with the earth wire Use an energy saver lamp

Explanation Fluorescent lamp use less power and economic (consume less power) compare to filament bulb. Less reflection on eyes and absorb less heat energy and good heat reflector The height of the lamp can be adjusted can be used anywhere Avoid short circuit and damage on the bulb Produce same brightness with less power consumption

64. Suggest the suitable design of fuse to protect an electrical equipment which is label 240V,2400W Suggestion Thin fuse wire Ceramic cartridge Fuse rating is 13A Low melting point Low specific heat capacity Metal is used Resistance to oxidation

Explanation Less space/to carry a limited electrical current/less mass hence low heat capacity/shorter time to heat up to melting point and blow Can withstand higher temperature because spark created by high voltage.240V can be huge Maximum rating must be sligthly higher than normal current For fast blow/melting faster when excessive current flow/easy to cut the current flow The fuse wire easily heated,melt and break the circuit Good electric conductor Does not interface with other function

65. You have to choose one of the cables to be used in the National Grid Network. Explain the suitability of each of the characteristics of the cables. Suggestion Diameter should be large density should be low

Explanation To reduce the resistance of the cable The cables will be lighter and can be

supportedsecurely So thre is less expansion and less sagging in the cables during hot days So the cables does not melt in high temperature

The rate of expansion should be low The melting point should be high

66. Explain the characteristic of electric pylon and the cable taht been use for electric transmission Suggestion Material: steel alloy V shape steel alloy Trust and supprt join Made from small diameter and laminated wire Cable made from low density material

67.

Explanation Strong,will not break easily Not too heavy Can support bigger weight Reduce addy current Cable is not heavy/ light weight

Investigate the characteristic of electric oven that can toast more cupcakes at

less time Suggestion The space inside oven is build bigger Increase the number of resistance heater at the top and bottom The wall is made of good insulator Fix a fan inside the oven Internal space of oven is painted silver Fix the step up transformer

Explanation It can fil up 180 slices of bread So it can supply enough heat Tyhe heat will not lost to surrounding Heat energy releaswed can spread uniformly in oven So the heat will radiated at wall and reflected back completely Oven can receive higher voltage and can function with higher power

68. Explain the designof electric kettle Suggestion Material of heating is made from nichrome High number of loop Use high power High melting point coil Low rate of rusting Use thermostat 3 plug in

Explanation To produces high heat energy To increase surface area so that more heat is released To produce more heat energy in the coil Nit easy melt under high temperature Does not get rust easily When temperatures reach 100oC If short circuit the overload current flows to earth(for safety reason)

69. Design incubator used to hatch eggs Suggestion Parallel circuit Multi storey rack Using fan Bulb with same brigthness and power Using alarm

Explanation When one bulb damage the another bulb still function/heat can distributed uniformly More eggs can be arranged heat can distributed uniformly heat can distributed uniformly To ensure that correct timing is employed in the hatching of eggs

70. Design circuit for cabin or house Suggestion connected in parallel Fit fuse at the live wire in the fuse box

Explanation Allow each electric appliances to be switched on and off independently To stop the flow of current by melting when a high voltage of electric current flows through the

Earth connection to the metal case of electrical appliances

Use low power lamps / install fluorescent lamp Regularly cleaning and removing dust from the air filters of air conditioners// Do not put more water in a kettle than needed for hot drinks

circuit // switches itself off very quickly if the current exceeds e.g. 15A (for 15A mcb) Earth wire connected to earth, so that when a fault occurs and a current flows through the live wire and the earth wire, the fuse in the live wire will blow and cut off the supply. It will protect a person who may touch a faulty or live appliance To save the energy To save the energy

CHAPTER 8 71. Suggest modification that need to be done on dc motor to increase efficiency of the motor. Suggestion Low density material Increase the number of turns in the coil Use high strength of magnets/ Add more magnets More segments Increase the magnitude of current

Explanation Coil hass smaller mass/ lighter Can increase magnitude of force/ higher electromagnetic field strength Increase the strength of magnetic field Coil rotates smoothly Can increase the magnitude of force/ can increase the strength of magnetic field

72. Investigate the design and the characteristic to improve the efficiency of transformer. Suggestion Use soft iron core Laminated core Use thick wire Use copper wire to make coil Wind the secondary coil on top of the primary coil

Explanation Easy to magnetized and demagnetized Less eddy current or reduce energy lost Reduce the resistance or more current flow Low resistance or reduce the lost of heat Reduce leakage of field lines

73. How to design a moving coil ammeter that can function better and able to detect small change of current? Suggestion Use stronger magnet Use curve magnet or concave Use cylindrical core Use soft iron core Use linear scale The sensitivity of moving coil galvanometer can be increased by increasing the strength of the radial magnetic field Using hairspring of lower stiffness Use lighter pointer Use a coil of a lighter mass Increase the area of coil

Explanation Strong magnetic field or larger rotation Produce radial magnetic field/to get linear scale To supply uniform magnetic field To concentrate the magnetic field The angle of rotation is linear Increase the force between the current carrying coil and magnetic field Smaller opposing force to stop turning of coil Smaller inertia easier to move Smaller inertia able to move easily More changes of magnetic flux,a bigger force are produce

74.

Suggest and explain the build of adaptor to charge the 8V handphone from 240V power supply. Suggestion

Explanation

Use step down transformer Ratio of turns 30 : 1 // 240V:8V Use four diodes Full wave rectifier Using a capacitor

Able to reduce voltage Can reduce voltage from 240V to 8V Full wave rectification To convert au current to dc current To smooth output current (steady direct current

CHAPTER 9 75. Suggest and explain the build of adaptor to charge the 8V handphone from 240V power supply Suggestion Use step down transformer Ratio of turns 30 : 1 // 240V:8V Use four diodes Full wave rectifier Using a capacitor

Explanation Able to reduce voltage Can reduce voltage from 240V to 8V Full wave rectification To convert au current to dc current To smooth output current (steady direct current

76.

Consult and modified the automatic switch light (diagram A) above which can switch on at night and switch off during morning to be automatic switch on fire alarm when there are fire , explain using diagram and the function of component. Suggestion Change R1 to termistor Change LED with alarm// siren

Explanation Thermistor can be detect heat from fire Able to produce sound of alarm if fire is detected Change LDR with R1 During fire, R1 has greater resistance compare to LDR so, no current flow When the temperature is high, the resistance of thermistor is low. This will increase the voltage acroos R1. So, currnt will flow to the base of transistor , than the transistor is switch on followed by greater increase in collecter current. The alarm will switch on.

12V,24W

77. Suggest the modification need to be done to the circuit in Diagram C so that it can function as automatically fire alarm switch that need high voltage. Suggestion Replace LDR with thermistor Replace bulb with siren/bell Connect relay switch to output transistor Interchange the position of resistor R and thermistor Use 240 V power supply

Explanation To detect heat when temperature is high To produce sound To switch on the siren To increase base voltage//voltage across R//base current Siren is function as high voltage

78. Modified the circuit 240V and Np = 4000 turns circuit to switch on 12V d.c radio.

Suggestion Step-down transformer Ratio of turns 20 :1 // 240:12 Np = 4000 turns and Ns = 200 turns Using four diodes Using a capacitor

79.

Explanation Capable of reducing potential difference / voltage Reduce potential difference 240V to 12V Full wave retification To smooth out output current // produce output to steady direct current.

Moving coil microphone

Suggestion use thin diaphragm Use strong material More number of turns of coil Thicker diameter of wire of coil Using more powerful magnet

Explanation Easy to vibrate Not easy to break Increase the rate of change of magnetic flux linkage // The magnitude of the induced current or is also increased reduce the resistance of the coil to increase the strength of the magnetic field.//Increase the rate of change of magnetic flux linkage//The magnitude of the induced current or induced electromotive force is also increased

CHAPTER 10 80. Explain the suitability of characteristic of radioisotopes to be used as treatment in brain tumor radiotherapy? Suggestion Short half life Gamma ray radiation Low ionozing power Liquid state of matter High penetrating power

Explanation Radioactive is dangerous substance, short half lfe can decay faster Gamma can kill cancerous cell and can penetrate skin of patient Minimum damage to tissue organ Easy to dissolve Can penetrate easily

81. Suggest and explain the safety ways, which are required when handling radioactive substance. Suggestion Use thick lead box Use forceps / robotic hand Wear photographic film Wear plumbum safety suit Use siren Packed into concrete drum and buried underground Always place GM detector nearby Label the radioactive container with symbol

Explanation Radioactive rays evem gamma cannot pass through Avoid direct touch Able to detect exposure radiations To protect the body from expose to radiation Faster warning when leakage Prevent the radioactive waste discharge to environment To detect the amount of radioactive nearby, for safety Easy to detect radioactive substance

82. Explain the suitability of characteristic odf radioisotope to be use in controliing the population of pest Suggestion Use gamma ray Solid state of matter Long half life High penetrating power High ionizing power

Explanation Able to mutate the insect Easy to handle Last longer Able to penetrate thick object/material Able to change// mutate the biology of insect

83.

. Explain the suitability of characterisitc of radioisotopes to be used in th trace of water pipeline. Suggestion Short lhalf life Few hour half life Beta particle or Gamma ray radiation Liquid state

84.

Explanation Radioactive is dangerous substance, short half life can decay faster - Enough time for worker to detect the pipe leakage - Radioactive uis dangerous Can penetrate pipe and soil, can be detected Can be inject and dissolve into water

Suggest the design of nuclear reactor.

Suggestion Use uranium-235 Nuclear fission Boron or Cadmium rad use as control rods Use moderator (graphitr) Bulid thick concrete wall Coarbon dioxide or water is use as coolong agent Use steam

Explanation Use as nucler fuel A lot of heat will produce To control the rate of nuvlear fission and to stop the radiation To slow the motion of neutron to the best reaction rate. So the rate of nuclear fission can be controlled Lead or thick concrete wall can prevent the escape of radioactive rays, keep the radiation inside the reactor To remove heat of reaction for turbine generator. This produce steam as heat carrier To turn the turbine and able to generate current

85.

Explain the suitability of charactersitic of radioisotopes to be used in sanitiza medical equip,ent Suggestion Gamma ray Longer half life Silid state of matter High penetrating power

Explanation Able to kill ant virus/ bacteria No need to change radioactive frequently Easy to handle Able to penetrate any equipment to sanitize

86. Explain the suitability of characteristics of radioisotope to be used in detecting the position of blood clot in veins (Deep vein thrombosis) Suggestion Use liquid state of matter Short half life Use beta ray Low ionizing power

Explanation Able to inject into patient body, dissolve easily Active in body in short time Able to penetrate skin Minimum damage to tissue organ

87. Explain the suitability of characteristics of radioisotope to be use in the trace of blockage in the kidney patient. Suggestion Use Iodine-123 Gamma ray Low energy Liquid state of matter Short half life

Explanation Used as nuclear imaging tracers to evaluate the anatomic and physiologyc function Able to penetrate trough body, bones and be detected Do not cause serious damage in cells Easy to inject to patient body Active in body in short time

88. Explain the suitability of characteristics of radioisotope to be use in control the thickness of paper in factory Suggestion

Explanation Can be used for long time, no need to replace frequently so, it save cost Can penetrate paper and be detected Easy to handle

Long half life Beta ray Solid state of matter

89. Explain the suitability of characteristics of radioisotope to be use in control the thickness of aluminium sheet in factory. Suggestion

Explanation Can be used for long time, no need to replace frequently7 so, it save cost Can be penetrate aluminium sheet and be detected Easy to handle, does not spill

Long half life Gamma ray Solid state of matter

MAKING DECISION-SECTION C Soalan ini berada di dalam Section C. Cadangan dan alasan dalam soalan ini juga boleh menggunakan contoh jawapan dalam soalan Modification.

90.

The transmission of electricity over the National Grid Network uses high voltage cables. You are assigned to study the characteristics of cables which could be used as transmission cable. Table 12 shows the characteristics of four transmission cables. Determine the most suitable transmission cable to be used and give reasons for your choice. Resistivity /ΩmCable Density / kg m-3 1 Cost Rate of thermal expansion P Q R S

3.0 1.8 7.5 7.0

x x x x

l0-7 l0-8 l0-7 l0-8

5 2 8 4

x x x x

l05 l03 l02 l03

Low Medium High Medium

High Low Medium High

Jawapan Characteristic Low resistivity Low density Low cost Low rate of thermal expansion Cable Q

Explanation To reduce heat loss in the cables The cables will be lighter Cost of project will be lower The cables will not expand under hot weather Low resistivity, low density, medium cost, low rate of thermal expansion

91. You are required to build a hydrometer that can be used to measure densities of concentrated acids.Table 11.1 shows the characteristics of 4 types of hydrometers L, M, N and O. Decide which hydrometer is most suitable and give reasons. Hydromet er L M N O

Type of material of hydrometer Plastic/Plastik Plastic/Plastik Glass / kaca Glass/ kaca

Diameter of capillary tube/ cm 0.5 2.0 0.5 2.0

Density of shots/ kgm-3 1000 1300 9800 8000

Diameter of bottom bulb/ cm 1.0 3.0 3.0 1.0

Jawapan Characteristic Material made from glass Small diameter of capillary tube High density of shots Big diameter of bottom bulb Choose N

Explanation Glass does not corrode with acid To increase the sensitivity of the hydrometer Makes the hydrometer stays upright To obtaine a bigger upthrust. N is made from glass, has small diameter of capillary tube, high density of shots and a big diameter of bottom bulb

92.

As a researcher , your duty is to study the characteristics of a material to make a water heater. You are given four choices of metal type T, U,V and W. The table below shows the characteristics of the four metals.Determine the most suitable metal to be used as the material to make the heater and give your reasons. al

Met T U V W

The cross sectional area Smaller Larger Smaller Larger

Melting Point Low High High High

Specific Heat Capacity High Low Low Low

Length Long Short Long Short

Jawapan Characteristic Smaller surface area High melting point Low specific heat capacity Long (coiled) metal Choose V

Explanation the resistance is higher not easy to melt the temperature arises shortly to increase the resistance because it has,smaller surface area, high melting point, low specific heat capacity and long metal

93.

You are given four choices of metals P, Q, R and S. The table below shows the characteristics for the four metals. Determine the most suitable metal to be used as the material to make the boat and give your reasons. Metal

Shape

P Q R S

Streamlined Oval Circle Streamlined

Density 900 452 387 500

Specific Heat Capacity Low High Low High

Strength High High High High

Jawapan Characteristic/cirri Streamline / larus Density /ketumpatan rendah

Reason/Sebab reduce the resistance of water/ higher buoyant force/ daya apungan tinggi

Specific heat capacity high /

absorbs heat slowly/serap haba dengan perlahan Difficult to damage / sukar rosak because its streamline,low density, high specific heat capacity and high strength

High strength / Kekuatan tinggi Choose S

94.

A student plans to fix a lamp in his room. Table 12.1 shows the features of 4 different types of lamps. Explain the suitability of each feature in Table 12.1 and then determine the most suitable lamp to be used. Give a reason for your choice Type of lamp Compact fluorescent lamp Filament lamp Long fluorescent lamp Round fluorescent lamp

Power 18 W

Efficiency 50 %

Life Span 7000 hours

Price High

75 W 20 W 24 W

12 % 45 % 40 %

1000 hours 14000 hours 10000 hours

Low Medium High

Jawapan Characteristic Low power lamp High efficiency

Explanation Safe cost//electric bill The room looks brighter//high output power//less power wastage No need to replace often Save money/cost Low power with highest efficiency, long hours of life span and low price

Long life span Low price Long fluorescent

95.

Table 11.1 shows 5 materials which can be used to make an optical fibre. You are asked to investigate the characteristics of the materials in Table 11.1 which could be used to make the optical fibre. Explain the suitability of each characteristic and hence, determine the most suitable material to be used to make the optical fibre. Give a reason for your choice. Material

Refractive index

% of light energy absorbed

Rigidity

Strength

P Q R S T

1.75 1.80 1.70 1.52 1.48

2% 10 % 2% 3% 10 %

Strong Weak Weak Strong Weak

Weak Strong Strong Strong Weak

Jawapan Characteristic High refractive index Small amount of light energy being absorbed by the material Material with weak rigidity Material with great strength Material R

Explanation Total internal reflection can occur easily The object under observation can be seen clearly // more light can be transmitted The optical fibre can be bent easily The optical fibre can last longer/not easily spoil High refractive index, low % of light energy absorbed, weak rigidity and great strength

96. You are asked to investigate the characteristics of hot air balloon as below. Explain the suitability for each characteristic for the hot air balloons and then determine which hot balloon will move up the fastest into the air. Give a reason for your choice

Jawapan Characteristic Volume of the balloon is high Density of the balloon material is low Gas temperature is high Total of mass is low Choose Q

Explaination Displace a larger amount of air/ Produce a higher buoyant force. Lower mass/Light Produce a maximum expansion of balloon. Upwards resultant force is higher/ Balloon move upwards faster. Because it has a high volume,the density of the balloon material is low,the gas temperature is high and the total mass is low.

97. Table 11.1 shows the characteristics of five types of materials that can be used for making the soles of the trekking shoes. You are asked to study the characteristics of the materials shown in Table 11.1. Explain the suitability of each characteristics in Table 11.1 and then determine the most suitable material to be used. Give a reason for your choice. Type of material P Q R S T

Density (Kg/m -3) 820 700 720 750 880

Number of studs x Area of 1 stud 6 x 30 cm2 8 x 30 cm2 5 x 30 cm2 4 x 30 cm2 3 x 30 cm2

Expansion effect Low Low Medium High High

Ability to stretch Good Good Average Poor Poor

Jawapan Characteristic Low density Many/fewer/very few studs Expansion effect is low Ability to stretch is good The most suitable material is Q

Reasons Small mass/light Gives extra/higher grip Always fits/Does not loosen when hot. Less stress on the feet/Can be pushed in all directions/ Can walk on uneven surface. Because it has a low density,many studs,low expansion effect and good ability to stretch.

98.

Table 12.2 shows the characteristics of five radioisotopes P, Q, R, S and T. As a factory engineer, you are required to determine the most suitable radioisotope that can be used by the system to ensure the volume of guava juice is uniform.Study the characteristics of all 5 radioisotopes and explain the suitability of the aspects.Determine the most suitable radioisotope and give the reason for your choice. Radioisoto pe

Half life Separuh

Types of ray Jenis sinar

State of matter

Ionising power Kuasa

Radioisoto p

hayat

P Q R S T

7 hours 10 days 100 days 10 years 30 years

alfa beta gamma gamma beta

Keadaan jirim

pengionan

solid liquid solid liquid solid

high moderate low high low

Jawapan

99.

You are assigned to investigate the design for the location to keep the boats andthe characteristics of the retaining wall as shown in Diagram 12.2 based on the following aspects: - the location to keep the boat - material used for the retaining wall - the height of retaining wall - size of slit Explain the suitability of the location and the characteristics of the retaining wall and determine the most suitable design to keep the boat safely. Characteristics Has a long half-life Emits beta Solid form Low ionising power Radioisotope T

Explanation Can be used for a long time hence save cost Can penetrate box and liquid and is less dangerous than gamma Easy to handle and contain. Does not change the state and taste of juice. It has long half life, emits beta, in solid form and has low ionising power.

Jawapan Characteristic Bay Concrete retaining wall High wall Smaller opening/aperture / slit of retaining wall Choose P

Reasons Wave is calmer Stronger/ / lasting Prevent high wave Diffraction obvious //low wave energy At bay, concrete retaining wall , high wall and smaller slit

100.

Diagram 11.4 shows five designs of ‘Newton’s Cradle’, P, Q, R, S and T, with different specifications. You are required to determine the most suitable design to make the ball at the end swings up to higher level and at bigger speed. Study all the five designs from the following aspects: − The arrangement of the balls − The type of material used to make the balls − the number of string used to hang the balls − the position of the ball to start the oscillation

Jawapan Characteristic The balls touch each other The type of material used to make the balls is steel Two strings used to hang each ball High position of the ball The most suitable design is Q

Reasons This will reduce losses of energy which will reduce the speed of the balls Steel balls are hard and produce highly elastic collision. Energy can easily propagates through the intermediate balls. This string arrangement restricts the balls’ movements to the same plane. the position of the ball to start the oscillation High potential energy and will change to high kinetic energy. The last end ball will swing at bigger speed. because the ball s touch each other, made from steel, use two strings attached to each ball and the initial position of the ball is high