Question

A heat engine has a cold reservoir of 250°C and a hot reservoir of 715°C. What is the efficiency of the engine?

A. 65.0%
B. 60.8%
C. 73.6%
D. 58.6%
E. 69.1%

Answer 1

715 - 250 = 465

715 x 0.65 = 464.75 = 465

Final Answer:

A. 65%

Answer 2

The efficiency of the engine is 47%.

Step-by-step explanation:

Given that,

Cold reservoir
`T_(1) = 250^(\circ)\ C`

`T_(1)=250+273=523\ K`

Hot reservoir
`T_(2) = 715^(\circ)\ C`

`T_(2)=715+273=988\ k`

The formula efficiency of the engine is defined as:

`\eta =(T_(2)-T_(1))/(T_(2))`

`\eta =1-(T_(1))/(T_(2))*100`

We substitute the value into formula

`\eta =1-(523)/(988)*100`

`\eta = 47\%`

Hence, The efficiency of the engine is 47%.