A diesel engine performs 2100 J of mechanical work and discards 4500 J of heat each cycle. Part A)

How much heat must be supplied to the engine in each cycle?

Part B)

What is the thermal efficiency of the engine?

(a) 6600 J

(b) 31.8%

Explanation:

work performed, W = 2100 J

Heat discard, Q2 = 4500 J

(a) Let Q1 be the amount of heat supplied

Work = Q1 - Q2

Q1 = Q2 + W = 4500 + 2100 = 6600 J

(b) efficiency = 1 - Q2 / Q1

Efficiency = 1 - (4500 / 6600) = 0.318 = 31.8 %