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.
