Question

An engine has a hot-reservoir temperature of 980 K and a cold-reservoir temperature of 570 K. The engine operates at three-fifths maximum efficiency. What is the efficiency of the engine?

Answer 1

Answer:

efficiency of engine is 0.21

Explanation:

given:

Th=980 K

Tc=570 K

since efficiency of engine is given as:

n=3/5*n_m

 =3/5(1-Tc/Th)

 =0.21

efficiency of engine is 0.21

Answer 2

Answer:

E = 0.251 or 25.1%

The efficiency of the engine is 0.251 or 25.1%

Explanation:

Maximum Efficiency of an engine can be expressed as;

Em = workdone/heat energy supplied

Em = 1 - Qc/Qh = 1 - Tc/Th

Given;

Tc = cold temperature = 570K

Th = hot temperature = 980K

Substituting the values;

Em = 1 - 570/980

Em = 0.4184

But the engine operates at three-fifths the maximum efficiency

E = 3/5 × Em

Substituting Em

E = 3/5 × 0.4184

E = 0.251 or 25.1%

The efficiency of the engine is 0.251 or 25.1%