Thermal Physics> A real engine has an efficiency of 33%. T...

A real engine has an efficiency of 33%. The engine has a work output of 24 j per cycle (a) How much hear energy is extracted from the high temperature reservoir per cycle
(A) 8 J
(B) 16 J
(C) 48 J
(D)72 J (E) the question can be answered only if the
engine is a carnot engine.
(b) How much heat energy is discharged into the low temperature reservoir per cycle?
(A) 8 J
(B) 16 J
(C) 48 J
(D) 72 J
(E) the question can be answered only if the engine is a carnot engine.
(c) For this engine T_L = 27ºC. What can be concluded about T_H?
(A) T_H = 450ºC
(B)T_H=177ºC.
(C) T_H > 177ºC.
(D)T_H
(E) 177ºC _H

Simran Bhatia , 9 Years ago

Grade 11

4 Answers

Aditi Chauhan

Last Activity: 9 Years ago

(a) The correct option is (D) 72 J.
The efficiency ε of a Carnot engine is defined as,

Urjita Sharma

Last Activity: 8 Years ago

As the formula of efficiency is only applicable to Carnot engines and as this is a real engine the first two questions cannot be answered. Thus option E for both.If it were a Carnot`s engine, then TH would have been 177°C . Considering a Carnot`s engine having The as 177 C would give efficiency of 33% but as this is a real engine its efficiency must be less than 33%. Hence if it is 33% then it`s TH must be greater than 177°C.

Urjita Sharma

Last Activity: 8 Years ago

The answer for first two can be given by the formula e= W/Qh1/3= 24/QhQh=72J1/3=1-Ql/QhQl= 48JPardon my previous answer was wrong.The third part is pretty much fine.

Urjita Sharma

Last Activity: 8 Years ago

For the third part, if the efficiency is less than a Carnot`s engine, for a Carnot`s engine its The would be 177C e=W/Qh Qh proportional to Th hence e is inversely proportional to Th thus as e is less than will be more than 177C