University Physics Volume 2

# Conceptual Questions

University Physics Volume 2Conceptual Questions

### 3.1Thermodynamic Systems

1.

Consider these scenarios and state whether work is done by the system on the environment (SE) or by the environment on the system (ES): (a) opening a carbonated beverage; (b) filling a flat tire; (c) a sealed empty gas can expands on a hot day, bowing out the walls.

### 3.2Work, Heat, and Internal Energy

2.

Is it possible to determine whether a change in internal energy is caused by heat transferred, by work performed, or by a combination of the two?

3.

When a liquid is vaporized, its change in internal energy is not equal to the heat added. Why?

4.

Why does a bicycle pump feel warm as you inflate your tire?

5.

Is it possible for the temperature of a system to remain constant when heat flows into or out of it? If so, give examples.

### 3.3First Law of Thermodynamics

6.

What does the first law of thermodynamics tell us about the energy of the universe?

7.

Does adding heat to a system always increase its internal energy?

8.

A great deal of effort, time, and money has been spent in the quest for a so-called perpetual-motion machine, which is defined as a hypothetical machine that operates or produces useful work indefinitely and/or a hypothetical machine that produces more work or energy than it consumes. Explain, in terms of the first law of thermodynamics, why or why not such a machine is likely to be constructed.

### 3.4Thermodynamic Processes

9.

When a gas expands isothermally, it does work. What is the source of energy needed to do this work?

10.

If the pressure and volume of a system are given, is the temperature always uniquely determined?

11.

It is unlikely that a process can be isothermal unless it is a very slow process. Explain why. Is the same true for isobaric and isochoric processes? Explain your answer.

### 3.5Heat Capacities of an Ideal Gas

12.

How can an object transfer heat if the object does not possess a discrete quantity of heat?

13.

Most materials expand when heated. One notable exception is water between $0°C0°C$ and $4°C,4°C,$ which actually decreases in volume with the increase in temperature. Which is greater for water in this temperature region, $CpCp$ or $CVCV$ ?

14.

Why are there two specific heats for gases $CpCp$ and $CVCV$, yet only one given for solid?

### 3.6Adiabatic Processes for an Ideal Gas

15.

Is it possible for $γγ$ to be smaller than unity?

16.

Would you expect $γγ$ to be larger for a gas or a solid? Explain.

17.

There is no change in the internal energy of an ideal gas undergoing an isothermal process since the internal energy depends only on the temperature. Is it therefore correct to say that an isothermal process is the same as an adiabatic process for an ideal gas? Explain your answer.

18.

Does a gas do any work when it expands adiabatically? If so, what is the source of the energy needed to do this work?

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