A car engine produces an average of 25 kW of power in a period of 10-min during which 1.25 kg of gasoline is consumed. If the heating value of gasoline is 43,000 kJ/kg, the effi…

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asked Jan 11, 2021 200k views

1 Answer

Dominik Honnef · Answer 1 · 2021-01-16T05:16:51+0000

Answer:B

Step-by-step explanation:

Given

Power Produced
$P=25\ kW$

time
$t=10\ min$

Gasoline consumed
$m=1.25\ kg$

Heat capacity of Gasoline
$C=43,000\ kJ/kg$

Heat Provided by Gasoline
Q_s=m* C

$Q_s=1.25* 43000=53,750\ kJ$

Energy used in Producing Power is
$W=25* 10* 60=15,000\ kJ$

Efficiency of an engine is

$\eta =(Work)/(Energy\ Supplied)$

$\eta =(15000)/(53750)=0.2790$

$\eta =27.90\approx 28\ \%$