ems tutorial.pptx

PREPARED BY EMS-CETSC PRESENTED BY JOHN ERIC FERRANCO

Introductory Concepts, Definition and Units

1.) 100g of water is mixed to 150g of alcohol (ρ=790kg/m3). Calculate a) the specific gravity (RD) of the mixture; b) the specific volume of the solution.

2.) A 45cm cube of ice melts, the liquid water is placed in a spherical container filling it. If  the specific volume of ice at 0 ⁰C is 1.094cm3/g and of water is 1.002cm3/g, determine the diameter of the spherical vessel used.

3.) A two compartment vessel contains a fluid in each section. For the first compartment the fluid density is 1200kg/m3 and of the second is 500kg/m3. The partition is removed and the fluid mix. Determine the density of the mixture if  a) the fluid masses are equal; b) the fluid volume are equal.

4.) A student on vacation went to scale Mt. Apo. His weight at the base of the mountain, where g=9.8m/s2 is 540N, on the top he weight 539.5N. Note that gravity acceleration decreases by 0.003m/s2 per 1000m ascent. Find the height in meters if  a) Mt. Apo; b) a point above the base where the weight of  an object decreases by 2%.

5.) A balloon is descending with a constant acceleration of 3.5m/s2. The mass of the balloon with its basket and content is 80kg. What mass of the ballast must be released so that the balloon will accelerate upward with a constant acceleration of 3.5m/s2? Neglect air resistance.

6.) A 40kN tank weighs 64kN when filled with kerosene and 70kN when filled with the same volume of water. Find the specific gravity of  kerosene.

7.) A solid cube material is 0.75cm on each side. If it floats in oil of density 800kg/m 3 with 1/3 of the block out of oil, what is the density of the material of the cube?

8.) The system shown is in equilibrium. Determine the diameter of the outside sphere if the submerged sphere has a diameter of  35cm.

9.) A block of wood with uniform horizontal section floats in water with 20cm projecting above the surface. The same block when placed in a body of oil (SG=0.8) floats with 18cm projecting above the oil surface. Determine the specific gravity of the wood.

10.) Determine the maximum weight W which could be carried by the 45kg composite piston shown, if the pressure of gas A is 350kPa, gas B and C have pressure of 170 and 500kPa, respectively. respectively.

11.) For the open manometer shown in the figure, what is the pressure in kPa at A (a=30cm; b=48cm; RDHg=13.59)

12.) For the differential manometer shown in the figure, determine the pressure difference between points X and Y when: Fluid X and Y is brine (RD=1.15), gage fluid is oil (RD=0.9) and z=90cm.

13.) CHALLENGE! A cubical block of wood 0.1m on a side and with a density of 550kg/m3 floats in a jar of  water. Oil with a density of 750kg/m 3 is poured on the water until the top of the oil layer is 0.035m below the top of the t he block. a) How deep is the oil layer? b) What is the gauge pressure at the block’s lower face?

Conservation of Mass and Energy

1.) Air flows through a compressor under steady flow condition. A suction: ν1=0.75m3/kg, υ1=30m/s. At discharge ν2=0.25m3/kg, υ2=40m/s. determine the diameter ratio of the discharge pipe to that of  the suction pipe.

2.) A 200g apple is thrown from the edge of a tall building with an initial speed of 20m/s. What is the change in kinetic energy of the apple if it strikes the ground at 50m/s?

3.) What retarding force is required to stop a 0.45 caliber bullet of mass 20g and a speed of 300m/s as it penetrates a wooden block to a depth of 2 inches?

4.) A 40g rifle bullet is fired with a speed if  300m/s into a ballistic pendulum of mass 5kg suspended from a chord 1m long. Compute the vertical height through which the pendulum rises.

5.) A force F inclined at 30⁰ with the horizontal moves an object horizontally a distance of 8m. Determine the work done if  F=7.5x+0.4x2, where F is in Newton and the x is in meter.

6.) A wooden spherical ball with specific gravity of 0.42 and a diameter of 30cm is dropped from a height of 4.2m above the surface of the water in a pool. If the ball barely touches the bottom of the pool, what is the water level in the pool at that point?

7.) A project engineer notices the site of a former sawmill along a river. Ruins of the original dam used as a hydropower source is still visible. The engineer decided to make some measurements to determine the maximum power that can be generated if the site were rehabilitated; the stream flow is found to be 25m3/s and the change in elevation is 4.87m. Determine the maximum power that could be produced.

8.) A 3kg block initially at rest us dropped from a height of 0.5m onto a spring whose scale is 2940N/m. Find the maximum distance x that the spring will be compressed. Assume g=9.8m/s 2.

9.) A gas contained in a piston cylinder has following initial properties: 3000kPa, 0.03m3. The gas is compressed during the process where PV1.4=C to a pressure of 9000kPa. The heat transfer from the gas is 3kJ. Determine the change in internal energy, neglect changes in kinetic and potential energies.

10.) Steam enters the turbine with a pressure P=4800kPa, u=2950kJ/kg, h=3300kJ/kg, and with a flow of 6kg/s. Steam leaves with h=2300kJ/kg, u=2100kJ/kg and P=22kPa. The radiative heat loss is equal to 24kJ/kg of  steam. Determine a) the power produced; b) the adiabatic power; c) the inlet specific volume; d) the exit velocity if the exit area is 0.5m2.

11.) Carbon Dioxide (ρ=1.8kg/m3) having an enthalpy of 96.5kJ/kg enters a compressor. It leaves with an enthalpy of 175kJ/kg. There is 35kJ/kg of heat lost from the compressor as CO2 passes through it. Neglecting changes in kinetic and potential energies, determine the power required for a flow rate of 0.2225m3/s.

12.) CHALLENGE! A centrifugal compressor compresses 5.7m3/min of air from 83kPaa to 620kPaa. The initial density is 1.27kg/m3 and the final density is 4.8kg/m3. The inlet suction line is 10cm in diameter and the discharge line is 5cm in diameter. Determine a) the mass flow rate; b) the change in flow energy between boundaries; c) the kinetic energy change.

Ideal Gas and Specific Heat

1.) If the initial volume of an ideal gas is compressed to one-half its original volume and twice its original temperature, the pressure is?

2.) A rigid vessel initially contains helium at 105kPaa and 15⁰C. Two kilograms of helium are then added to the contents so that the final pressure and temperature are 200kPaa and 20⁰C. Determine a) the volume of the vessel; b) the final mass of helium.

3.) A rigid vessel initially contains hydrogen at 200kPaa and 20⁰C. Two kilograms of  hydrogen are then pumped out so that the final pressure and temperature is at 105kPaa and 15⁰C. Determine a) the final mass of hydrogen; b) the volume of the vessel.

4.) A 1500L tank contains nitrogen at a pressure of 400kPag and a temperature of  320K. Later, because of a leak, it was found that the gage pressure has dropped to 320kPag and the temperature has decreased to 300K; determine a) the initial mass of nitrogen; b) the remaining nitrogen; c) the amount of nitrogen that has leaked out.

5.) A bicycle pump is full of air at atmospheric pressure. pressure. The length of stroke of  the pump is 45cm. At what part of the stroke does the air begin to enter the tire in which the gage pressure is 310kPag? Assume compression is isothermal.

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6.) An air bubble rises from the bottom of a well where the temperature is 27 ⁰C. Find the percentage increase in volume of the bubble if the depth of the well is 5m. Atmospheric pressure is 101.528kPaa.

7.) A 15cm diameter x 100cm length cylindrical steel vessel contained nitrogen at 1315kPag and 28⁰C. After some of the nitrogen was used the pressure and temperature dropped to 480kPag and 22⁰C. a) What proportion of nitrogen was used? b) What volume would the used nitrogen occupy at 1atm and 15.5⁰C?

8.) A 0.8m diameter sphere contains helium at 20bar and 28⁰C. How many cylindrical drums 12cm in diameter and 70cm long, which is initially devoid of any gas, can be filled to a pressure of 3bar at 18 ⁰C? Assume the helium in the sphere remains at 28⁰C.

9.) Complete the following ideal gas table:

10.) 8kg of a gas, R=280J/kg.K and Cv=0.78kJ/kg.K undergo a reversible nonflow constant pressure process from V1=1.2m3, P1=700kPaa to a state where T2=480⁰C. Find a)ΔU, ΔH, Q, Wnf ; b) if the process has been a reversible steady flow type with ΔP=0 and ΔK=0, find Wsf .

11.) A 0.064kg of octane vapor (MW=114) is mixed with 0.91kg of air (MW=29) in the manifold engine. The total pressure of the manifold engine is 86.1kPa and the temperature is 290K. Assume octane behaves ideally. What is the partial pressure of the air in the mixture in kPa?

12.) 5kg of O2, 0.5kg of CO2 and 8.5kg of N2 are mixed at constant temperature until the mixture pressure is constant at 690kPaa. Determine a) the partial pressure of each gas; b) the molecular weight of the mixture; and c) the gas constant of the mixture.

13.) It is desired to produce a gas mixture containing 35% by volume of CO2 and 65% by volume of oxygen. If there is 1.4kg of CO 2 in the mixture, find a) mass of O2 in the mixture; b) the gas constant of the mixture.

14.) CHALLENGE! A valve joins a two compartment adiabatic tank. 0.75 kg of  nitrogen dioxide at 4500kPaa and 400K is contained in one compartment while 0.45kg of air at 550kPaa and 300K is contained in the other compartment. The valve is opened and the gasses mix. Determine a) the gas constant for the mixture; b) the final temperature and pressure of the mixture.