Questions from Modern Physics

Q: In Example 20.4, a Carnot refrigerator requires a work

In Example 20.4, a Carnot refrigerator requires a work input of only 230 J to extract 346 J of heat from the cold reservoir. Doesn’t this discrepancy imply a violation of the law of conservation of en...

Q: On a sunny day, large “bubbles” of air form

On a sunny day, large “bubbles” of air form on the sun warmed earth, gradually expand, and finally break free to rise through the atmosphere. Soaring birds and glider pilots are fond of using these “t...

Q: How can the thermal conduction of heat from a hot object to

How can the thermal conduction of heat from a hot object to a cold object increase entropy when the same amount of heat that flows out of the hot object flows into the cold one?

Q: The free expansion of an ideal gas is an adiabatic process and

The free expansion of an ideal gas is an adiabatic process and so no heat is transferred. No work is done, so the internal energy does not change. Thus, Q/T = 0, yet the randomness of the system and t...

Q: Are the earth and sun in thermal equilibrium? Are there entropy

Are the earth and sun in thermal equilibrium? Are there entropy changes associated with the transmission of energy from the sun to the earth? Does radiation differ from other modes of heat transfer wi...

Q: Give two examples of reversible processes and two examples of irreversible processes

Give two examples of reversible processes and two examples of irreversible processes in purely mechanical systems, such as blocks sliding on planes, springs, pulleys, and strings. Explain what makes e...

Q: Suppose that you put a hot object in thermal contact with a

Suppose that you put a hot object in thermal contact with a cold object and observe (much to your surprise) that heat flows from the cold object to the hot object, making the cold one colder and the h...

Q: If you run a movie film backward, it is as if

If you run a movie film backward, it is as if the direction of time were reversed. In the time-reversed movie, would you see processes that violate conservation of energy? Conservation of linear momen...

Q: The gas used in separating the two uranium isotopes 235U and 238U

The gas used in separating the two uranium isotopes 235U and 238U has the formula UF6. If you added heat at equal rates to a mole of UF6 gas and a mole of H2 gas, which one’s temperature would you exp...

Q: A system is taken from state a to state b along the

A system is taken from state a to state b along the three paths shown in Fig. Q19.23. (a). Along which path is the work done by the system the greatest? The least? (b). If Ub > Ua, along which pa...