Question

A particular engine has a power output of 5 kW and an efficiency of 30%. If the engine expels 6464 J of thermal energy in each cycle, find the heat absorbed in each cycle. Answer in units of J.

Answer 1

Answer:

The heat absorbed in each cycle is 9,234.286 J

Explanation:

Given;

power output, P = 5 kW = 5,000 W

efficiency of the engine, e = 30 % = 0.3

thermal heat expelled, $Q_c$ = 6464 J

let the heat absorbed = $Q_h$

The efficiency of the engine is given as;

$e = \frac{W}{Q_h} = \frac{Q_h-Q_c}{Q_h} = \frac{Q_h}{Q_h} - \frac{Q_c}{Q_h} = 1-\frac{Q_c}{Q_h}\\\\e = 1-\frac{Q_c}{Q_h}\\\\0.3 = 1-\frac{Q_c}{Q_h}\\\\\frac{Q_c}{Q_h} = 1-0.3\\\\\frac{Q_c}{Q_h} = 0.7\\\\Q_h = \frac{Q_c}{0.7} \\\\Q_h = \frac{6464}{0.7} = 9,234.286 \ J.$

Therefore, the heat absorbed in each cycle is 9,234.286 J.