The units for efficiency are:

A$.$ J

B$.$ W

C$.$ J$/$W

D$.$ No units

$2.$ An engine takes $3,000$ J from a hot reservoir and expels $2,400$ J to a cold reservoir. How much work

does the engine do$?$ Express your answer in Joules and input the number only.

$3.$ An engine takes $3,000$ J from a hot reservoir and expels $2,400$ J to a cold reservoir. What is the

thermal efficiency of the engine?

A$.20\%$

B$.45\%$

C$.60\%$

D$.80\%$

$4.$ Three engines operate between reservoirs separated in temperature by $300$ K$.$

Engine A: TH $=1000$ K$,$ TC $=700$ K

Engine B: TH $=900$ K$,$ TC $=600$ K

Engine C: TH $=500$ K$,$ TC $=200$ K

Rank the engines by their maximum possible efficiencies.

A$.$ A $>$ B $>$ C

B$.$ A $>$ C $>$ B

C$.$ B $>$ A $>$ C

D$.$ B $>$ C $>$ A

E$.$ C $>$ B $>$ A

F$.$ C $>$ A $>$ B