A gasoline engine with efficiency 25% delivers 1500 J of mechanical work per cycle. How much heat does this engine discard per cycle? (A) 6000 (B) 7500J (C) 4500J (D) 375 (E) 2000

(C) 4500J

Explanation:

η = Efficiency of the gasoline engine = 25% = 0.25

W = mechanical work done by engine per cycle = 1500 J

E = Total input heat

mechanical work done by engine per cycle is given as

W = η E

1500 = (0.25) E

E = 6000 J

U = heat discarded by the engine per cycle is given as

U = E - W

U = 6000 - 1500

U = 4500 J