physics paper 3 csec

CXC CSEC Physics | Paper 03 | 2002

1.

(a)

State the law of conservation of energy and differentiate between kinetic and potential energy. (3 marks)

(b)

A spring-mass system oscillates between X and Y on a frictionless table as shown in Figure 1.

Describe what energy transformations take place as the mass travels from X to Y. O is the equilibrium position of the spring. (5 marks)

(c)

A 0.5 kg block slides from rest down an inclined plane as shown in Figure 2. The velocity at the bottom of the plane is 6 ms -1 . The vertical distance PO is 2.0 m 2 (g = 10 ms- )

(i)

Calculate the potential energy at the top of the incline and the kinetic energy at the bottom of the incline.

(ii)

Why are these answers in part (i) different?

(iii)

If the block were to be dropped from P, what would be its velocity at 0?

(iv)

If part (iii) were performed on the moon where g = 2 ms -2, explain whether the velocity at O would be greater or lesser than the velocity obtained in part (iii). (12 marks) Total 20 marks Formatted by: ReThink Physics | www.rethinkphysics.blogspot.com

CXC CSEC Physics | Paper 03 | 2002 2.

(a)

Describe an experiment to verify Snell's law of refraction. State what apparatus you would use, give a brief description of the method you would use and state how you would arrive at your conclusion. (8 marks)

(b)

An optical device consists of two glass blocks of different indices of refraction, arranged as shown in Figure 3. The refractive index from air to Medium 1 is 1.2. The refractive index from Medium 1 to Medium 2 is 1.25.

(i)

If light is incident at 600 on the block with the smaller refractive index, determine the angles 1, 2 , 3, 4 , and 5 .

(ii)

What is the velocity of light in Medium 1? c = 3 x l08ms-1 (12 marks) Total 20 marks

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CXC CSEC Physics | Paper 03 | 2002 3.

(a)

Figure 4 shows a simplified diagram of a permanent magnet d.c. motor (seen from one end) in which a rectangular coil is suspended in a uniform magnetic field.

(i)

Copy this diagram into your answer booklet. On your diagram, draw the forces which turn the coil. These forces make up a couple that causes rotation of the coil. Will the coil rotate in a clockwise or anticlockwise direction? Indicate on your diagram the coil position which gives maximum value of the couple.

(ii)

How would the speed of the motor be affected by an increase in the supply voltage? Explain.

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(8 marks)

CXC CSEC Physics | Paper 03 | 2002 (b)

Electricity can be generated by passing a conducting liquid through a very strong magnetic field. The electrical energy is extracted by suitably placed electrodes as shown in Figure 5.

(i)

By considering an element of fluid, XY, in the shape of a cylindrical rod, determine the direction of current flow through the load RS. Give the name of the rule you use.

(ii)

In one version of this type of generator the conducting liquid is pumped through the electrodes in a continuous circulating loop, thereby producing a d.c. output. Explain why this arrangement produces only a d.c. output.

(iii)

Suggest TWO possible modifications to the operation of this generator which would result in an a.c. output. Select any ONE of your suggestions and explain why it would work.

(iv)

Suppose the liquid was not pumped and the load RS replaced by a battery. Would the liquid move? Explain. What would be the overall effect of this change? (12 marks) Total 20 marks

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CXC CSEC Physics | Paper 03 | 2002 4.

(a)

What are the TWO principal ideas of the kinetic theory of matter? Describe the kinetic theory model of the three states of matter. (8 marks)

(b)

(i)

Heat must either be added or removed to convert one state of matter to another. Calculate the amount of heat energy which must be added to 2.5 kg of water at its boiling point in order to evaporate it completely. (Specific Latent Heat of vaporization of water = 2 260 000 J kg-1)

(ii)

It is observed that the specific latent heat of vaporization is greater than the specific latent heat of fusion for most substances. Use kinetic theory to explain this in terms of the separation of the particles in each state. (6 marks)

(i)

If the steam in part (b) (i) were captured in a closed container at 100 0 C and then heated, the pressure in the container would be observed to increase. Use kinetic theory to explain this effect.

(ii)

When a drop of a strongly coloured liquid (such as potassium dichromate - a bright yellow liquid) is added to a beaker of water, it is found that after some time the entire contents of the beaker become a uniform colour. Use kinetic theory to explain this phenomenon. (6 marks) Total 20 marks

(i)

Describe an experiment to determine the position of the centre of gravity of a metal sheet of uniform thickness. Your account should include the apparatus you would use and a brief account of a suitable procedure.

(ii)

State the condition which the position of the centre of gravity of a body must satisfy in order that the body be stable. (8 marks)

(c)

5.

(a)

(b)

Two uniform planks each of mass 10 kg and length 2 m are arranged as shown in Figure 6.

(i)

Find the maximum value of x for which the top plank will remain in equilibrium.

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CXC CSEC Physics | Paper 03 | 2002 (ii)

(c)

A 15 kg mass is placed at P. Draw a diagram showing the forces acting on the upper plank when it is just about to topple. Use your diagram to calculate the value of x for which the upper plank just begins to topple. (8 marks)

Two uniform rods both of length 2 m are arranged at right angles as shown in Figure 7, D and E are the mid-points of rods AC and AD respectively.

(i)

(ii)

In your answer booklet, draw a well labelled diagram of the arrangement, showing the line of action of the weight of the arrangement relative to A, B, C, D and E when it is a)

suspended from A and in equilibrium

b)

suspended from D and in equilibrium.

Hence, labelled diagrams of the arrangement as shown in Figure 7 and clearly indicate the position of the centre of gravity of the arrangement relative to A, B, C,D and E. (4 marks) Total 20 marks END OF TEST

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