Question

When a certain ideal engine performs 2000 kJ of work, 4750 kJ of heat flows out of the engine at 275°C. (a) How much heat flows into the engine? (b) What is the efficiency of the engine? (c) At what temperature does heat flow into the engine?

Answer 1

Answer:

a) Qh= 6750 kJ

b) e = 0.296

c) $T_H$ = 390.625° C

Explanation:

Given:

Work done, W = 2000 kJ

Heat flow, Q = 4750 kJ

Temperature at which heat flows out, $T_c$ = 275° C

a) Now, the heat flow through the engine (Qh)

Qh = W + Q

or

Qh = 2000 + 4750

or

Qh= 6750 kJ

b) The efficiency (e) is given as:

$e=\frac{W}{Q_h}$

on substituting the values, we get

$e=\frac{2000}{6750}$

or

e = 0.296

c) $e=1-\frac{T_c}{T_H}$

where,

$T_H$ is the temperature at which heat flow

on substituting the values, we get

$0.296=1-\frac{275}{T_H}$

or

$T_H$ = 390.625° C