Page 270 - Schaum's Outline of Theory and Problems of Applied Physics

CHAP. 21] THERMODYNAMICS 255

Multiple-Choice Questions

21.1. A heat engine takes in heat at one temperature and turns
(a) all of it into work
(b) some of it into work and rejects the rest at a lower temperature
(c) some of it into work and rejects the rest at the same temperature
(d) some of it into work and rejects the rest at a higher temperature

21.2. A process that can be reversed without energy input from an outside source is one that takes place at constant
(a) pressure (c) velocity
(b) density (d) temperature

21.3. In an adiabatic process in a system,
(a) its temperature stays the same
(b) its pressure stays the same
(c) no heat enters or leaves it
(d) no work is done by or on it

21.4. Without work being done on it, a gas cannot be
(a) compressed isobarically (c) compressed adiabatically
(b) compressed isothermally (d) expanded adiabatically

21.5. To be completely efficient (which is impossible), the exhaust temperature of a frictionless heat engine would have
to be
(a)0 K
(b) 273 K
(c) less than its intake temperature
(d) the same as its intake temperature

21.6. The Carnot cycle does not include an

(a) isobaric expansion (c) adiabatic expansion
(b) isothermal expansion (d) adiabatic compression

21.7. The efficiency of a Carnot engine operating between the absolute temperatures T 1 and T 2 is

(a) equal to T 2 /T 1
(b) 100%
(c) the maximum possible between these temperatures
(d) the same as that of an actual engine operating between these temperatures

21.8. Which of the following engines is the most efficient?
(a) gasoline engine (c) steam engine
(b) diesel engine (d) Carnot engine

21.9. The fuel in a diesel engine is ignited by
(a) a spark plug
(b) the hot air into which it is injected
(c) being compressed until it is hot enough
(d) exhaust gases left over from the previous cycle