15 misconceptual questions

About what percentage of the heat produced by burning gasoline is turned into useful work by a typical automobile?

20%

A heat engine operates between a high temperature of about 600C and a low temperature of about 300C. What is the maximum theoretical efficiency for this engine?

About 34%

Which statement is true regarding the entropy change of an ice cube that melts?

Entropy increase

Which of the following possibilities could increase the efficiency of a heat engine or an internal combustion engine?

Increase the temperature of the hot part of the system and reduce the temperature of the exhaust Decrease the temperature of both the hot part and the exhaust part of the system by the same amount

In an isobaric compression is an ideal gas

Work is done on the gas

An ideal gas undergoes and isothermal process. Which of the following statements are true? (i) No heat us added to or removed from the gas. (ii) The internal energy of the gas does not change. (iii) The average kinetic energy of the molecules does not change.

(i) F (ii) T (iii) T

Which is possible: converting (i) 100J of work entirely into 100J of heat, (ii) 100J of heat entirely into 100J of work?

Both are possible

An ideal gas undergoes an adiabatic expansion, a process in which no heat flows into or out of the gas. As a result,

Both the temperature and pressure of the gas decrease

On a very hot day, could you cool your kitchen by leaving the refrigerator door open?

No, the heat exhausted by the refrigerator into the room is more than the heat the refrigerator takes out of the room

An ideal gas undergoes an isothermal expansion from state A to state B. In this process (use sign conventions, page 413).

Q>0, change in U=0, W>0

An ideal gas undergoes an isobaric compression and then an isovolumetric process that brings it back to its initial temperature. Had the gas undergone one isothermal process instead,

The work done on the gas would be greater