Answer to Question #41169 in Physics for suleman

Question

1 The first law of thermodynamics is a restatement of which of these laws?
conservation of charge
conservation of momentum
conservation of entropy
conservation of energy

2 An engine absorbs 2000J of heat from a hot reservoir and expels 750J to a cold reservoir during each operating cycle. What is the power output of the engine if each cycle lasts for 0.5 seconds?
750W
1750W
3000W
2500W

3 An engine absorbs 2000J of heat from a hot reservoir and expels 750J to a cold reservoir during each operating cycle. How much work is done during the cycle?
1250J
750J
2000J
350J

4 An engine absorbs 2000J of heat from a hot reservoir and expels 750J to a cold reservoir during each operating cycle. What is the efficiency of the engine?
50%
62.5%
74.2%
85.6%

5 Which of the following substances has the highest viscosity at room temperature?
Water
kerosine
palm oil
alcohol

6 Tinny insects such as mosquitoes can seat on the surface of water. Which physical principle makes this possible?
gravity
surface tension
centrifugal action
upthrust

7 Which of these is correct about viscosity?
it increases with increase in temperature
it varies with the relative velocity of the surfaces in contact
it is does not vary from one liquid to another
both viscous force and upthrust act upwards

8 The molecules of a liquid and those of an object on it spills are held together by what type of forces?
cohesive forces
adhesive forces
viscosity
surface tension forces

9 A string of natural length L extends to a new length L' under tensile force F. If Hooke’S law applies, the work done in stretching the spring is ------------
1/2FL
1/2FL'
1/2 F(L-L')
F(L-L')

10 A wire of cross-sectional area of

and length 50cm stretches by 0.2mm under a load of 3000N. Calculate the Young’s modulus for the wire





11 If a force of 80N extends a spring of natural length 8m by 0.4m what will be the length of the spring when the applied force is 100N
0.3m
0.5m
1.0m
2.0m

12 In conduction, thermal energy is transported by
the movement of a fluid
the collision of particles
electromagnetic fields
the propagation of sound waves

13 If the volume of a gas is

at

C and 380mm of mercury, calculate the volume of this gas at s.t.p





14 One of these is an example of thermal radiation detector
bolometer
thermometer
thermal rod
thermal glass

15 One of these is NOT a basic assumption of kinetic theory of ideal gases
a gas consist of a large number of molecules
the attraction between the molecules is negligible
the kinetic energy of the molecules is changing continuously
the gas molecules are in a state of continuous random motion

16 Thermal expansion of a solid material depends on the following EXCEPT
the nature of the material making up the solid
the range of the temperature change
the initial dimensions of the solid
average translational motion of constituent atoms of the material

17 An electric kettle contains 1.5 kg of water at

C and powered by a 2.0 kW electric element. If the thermostat of the kettle fails to operate, approximately how long will it take for the kettle boil dry? (Take the specific latent heat of vaporization of water as

500s
1000s
1500s
3000s

18 Calculate the work done against external atmospheric pressure when 1 g of water changes to

of steam. Take the atmospheric pressure as

169.3 J
342.4 J
226.2 J
143.5 J

19 The statement "Heat lost by hot object is equal to heat gained by cold object" another way of expressing the law of conservation of ---------------------
charge
angular momentum
energy
momentum

20 Which of the following does NOT determine the amount of internal energy an object has?
temperature
amount of material
type of material
shape of the object

Answer 1

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