A gasoline engine in a large car takes in 10,500J of heat and delivers 2450J of

Question

A gasoline engine in a large car takes in 10,500J of heat and delivers 2450J of

mechanical work per heat cycle. The heat energy is converted by burning gasoline.

The conversion rate, the heat of combustion is 5 x 104 J/g.

(a)What is the thermal efficiency of the engine?

(b)How much heat is returned to the cold reservoir?

c)How much gasoline is burned during each cycle?

(d) If the engine goes through 30 cycles per second, what is the power output of the

engine?

(d2)How much gasoline is burned per hour?

Explanation / Answer

a)

e = W/Qh = 2450/10500 = 23.3 %

b)

Qc = Qh - W = 10500 - 2450 = 8050 J

c)

m = 10500/5e4 = 0.21 grams

d)

P = W/t = 2450/(1/30) = 73500 Watts

e)

0.21 * 30 * 60 * 60 = 22680 grams = 22.7 Kg

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