Question

if you had a steam engine working between 300c and 20c what is its maximum efficiency? If you had a gas engine working between 1000c and 150c what would its maximum efficency be?In each case if Qh=800J what would be Wmax be?

Answer 1

here,

Tc = 20 degree C = 293 K

Th = 300 degree C = 573 K

maximum efficiency = 1 - Tc/Th

maximum efficiency = 1 - 293/573

maximum efficiency = 0.49

the maximum efficiency is 0.49
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for Wmax = 0.49 * 800 = 392 J

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Tc = 1000 degree C = 1273 K

Th = 150 degree C = 423 K

maximum efficiency = 1 - Tc/Th

maximum efficiency = 1 - 423/1273

maximum efficiency = 0.667

the maximum efficiency is 0.667

for Wmax = 0.667 * 800

Wmax = 534 J

the work Wmax is 534 J