Answer to Question #179020 in Molecular Physics | Thermodynamics for Jasper

Question

You are with your father with his motorbike on the way to your school, in the middle of your travel, the gas was empty. Luckily there is a gas station nearby. Your father asked you to buy 2 liters of 100 worth money per liters "premium" gasoline advertised with r=13. But you choose to buy 93 worth of money per 2 liters ordinary fuel with r=8. How much decrease in the ideal efficiency results from this decrease in the compression ratio? Use y=1.40. Is it greater that the difference in price?

Answer 1

Thermal efficiency = $1 - (\dfrac{1}{r^{\gamma -1}})$

for r = 13

Thermal efficiency = $1 - (\dfrac{1}{13^{1.4-1}})$ = $1 - (\dfrac{1}{13^{0.4}})$ = 0.642

for r = 8

Thermal efficiency = $1 - (\dfrac{1}{8^{1.4-1}})$ = $1 - (\dfrac{1}{8^{0.4}})$ = 0.565

$\therefore$ The decrease in efficiency is 0.642 - 0.565 = 0.077