Physics Test Fusion
1. The internal energy of a balloon changes by 100 J. The work done on the environment
around it is 70 J. How much heat does the balloon gain? 170 J 30 J -170 J XXXXXXXXXXA hot ai
alloon is heated so that the change in internal energy is 100 J. If the heat lost to the
environment is only 20 J, what is the work done on the atmosphere? -80 J 80 J 180 J -180 J 3.
In an adiabatic process, the first law of thermodynamics simplifies to: ΔU=−W W=Q ΔU=Q
ΔU=W 4. Heat engines are devices that turn heat into: Work Internal Energy External Energy
Matter 5. Which of the following would transform heat into work? Check any that apply. Hero’s
Engine Steam Engine Four-stroke internal combustion Engine Battery Engine 6. If you squeeze
a gas inside of a cooler, meaning it cannot gain or lose heat, what must be true? Check all that
apply. Internal Energy increases Temperature increases Work done on gas is negative
Temperature decreases 7. An engine is not functioning properly and does no work. What can
you say about this from the first law of thermodynamics? ΔU=Q ΔU=−W Q=W ΔU does not
change 8. ΔU=Q is indicative of an ______________ process. Isovolumetric Isothermal
Adiabatic Isotropic 9. In cooling down milk, the internal energy changes by -400 J. If -450 J of
heat was abso
ed by the fridge, how much work was done on the milk? -50 J 50 J 950 J -950 J
10. A system has energy given to it, and the system uses a bit of that energy to do work on the
environment. The internal energy must have: Decreased Increased not changed oscillated 11.
Which processes are increases in entropy in a substance? Check all that apply. boiling wate
urning wood freezing ice deposition of water vapor 12. An engine uses 1 kJ of energy to run
ut is only 72% efficient. What is the useful work you can expect from the engine? 720 J 172 J
180 J 72 J 13. The effort to build an engine which is 100% efficient is: Not Possible Possible Will
e achieved some day Is slightly delayed 14. A car motor releases 700 J of energy into the
cooling system. It is a combustion motor which is 50% efficient. What amount of work could you
expect from the motor? 700 J 1400 J 2100 J 350 J 15. Describe how entropy is decreased by
inging a substance from a gas, to a liquid, and finally to a solid. Be sure to use the terms
order, disorder, energy, and entropy
1. Explain how the Law of Conservation of Energy and the 1st Law of Thermodynamics of
Equation are related. Express this relationship in the form of an equation. (5 pts.) 2. Explain the
2nd Laws of Thermodynamics in your own words. Using these definitions explain why a
perpetual motion machine is not practically possible and explain how Maxwell’s Demon relates
to the 2nd law of Thermodynamics. James C. Maxwell created a thought experiment (Gedanken
experiment) involving a demon. This demon controls a small door between two chambers of
gas. As individual gas molecules approach the door, the demon quickly opens and shuts the
door so that fast molecules pass into the other chamber, while slow molecules remain in the first
chamber. (5 pts.) 3. Why is it not possible for all of the energy transfe
ed as heat from a
high-temperature source to be expelled from an engine by work? (5 pts.)
1. The human body may seem to be a perfectly efficient system, but there is a source of energy
input, to keep a human body running at maximum efficiency. This energy comes from: Food
Discussions UV radiation Sleep 2. Entropy is always: Increasing Decreasing Creating orde
Spontaneously flowing 3. If you randomly shuffled a deck of 52 cards, what is the likelihood that
they would come together in perfect order by number and suit? 152! XXXXXXXXXX! 4. You are
the lucky person who witnesses a miracle: You have placed water into your freezer and
witnessed it becoming ice. Entropy increase has been reversed. Where did the entropy go? Out
the freezer exhaust Out the chimney To the cu
To another item in the freezer 5. Which are
examples of entropy increasing? Check all that apply. A liquid becoming a gas A solid becoming
a liquid Wood burning in a fire Water vapor condensing on a humid day. 6. An engine is 34%
efficient. What ratio of work to heat input is possible? XXXXXXXXXX XXXXXXXXXXAn engine is
able to do 1000 J of work. How much heat would need to be added for it to be as efficient as an
electric motor? 1250 J 1550 J 800 J 8000 J 8. An engine does 90 J of work and requires 450 J
of energy to run each cycle. What type of engine is it most likely to be? Combustion Electric
Fast Slow 9. Decreasing the internal energy of a substance: Decreases entropy in the
substance Increases entropy in the substance Keep the entropy constant in the substance
Changes nothing. 10. A boiler does 1 kJ of work and then the heat of the exhaust is measured
to be 100 J. What is the efficiency of the boiler? 90% 10% 110% -10% Questions: 1. The first
law of thermodynamics states that you cannot obtain more energy from a process than you
originally put in. The second law states that you cannot obtain as much usable energy from a
system as you put into it. Explain why these two statements do not contradict each other. 2.
What conditions are necessary for a heat engine to have an efficiency of 1.0? 3. In which of the
following systems is entropy increasing? (Do not include the su
oundings as part of the
system.) a. An egg is
oken and scrambled. b. A cluttered room is cleaned and organized. c. A
thin stick is placed in a glass of sugar-saturated water, and sugar crystals form on the stick. 4.
Why is it not possible for all of the energy transfe
ed as heat from a hightemperature source to
e expelled from an engine by work?