A Carnot engine takes in heat from a reservoir of heat at `427^(@)C`. How many calories of heat must it take from the reservoir in order to procuce useful mechanical work at the rate of `357 watt`?

Options

A. 150 cal/s
B. 160 cal/s
C. 170 cal/s
D. 180 cal/s

Answer

C

Explanation

`T_(1)=427+273=700K`
`T_(2)=273+77=350`
`thereforeeta=1-T_(2)/T_(1)=1-350/700=1/2`
`thereforeeta=W/Q_(1)`
`thereforeQ_(1)=W/eta=357/(1//2)=714J//s`
`thereforeQ_(1)=714/4.2=170cal//s`