Work Energy And Power Question 274

Question: The energy content of gasoline is $ 3.6\times 10^{7}J/L $ . A motor with an efficiency of 20% is needed at fall output power of 45 kW for 50.0 minutes. How many litres of gasoline are required to operate the motor for this amount of time?

Options:

A) 0.31 L

B) 0.38 L

C) 1.6 L

D) 19 L

Show Answer

Answer:

Correct Answer: D

Solution:

[d] $ E=Pt=45\times 10^{3}\times 50\times 60=1.35\times 10^{8} $

$ V=\frac{1.35\times 10^{8}}{3.6\times 10^{7}}=3.75L $ Since the motor is 20% efficient, five times as much gasoline is needed.



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