Answer:
The efficiency of each cycle of a heat engine is 30 %.
Explanation:
Given that,
Heat absorbed by a heat engine, Q = 64 kcal
Heat exhaust by a heat engine, Q' = 42 kcal
We need to find the efficiency of each cycle. The efficiency of heat engine is defined as the ratio of work output to the energy supplied. It is given by :
[tex]\eta=1-\dfrac{Q'}{Q}[/tex]
[tex]\eta=1-\dfrac{42}{64}[/tex]
[tex]\eta=0.3[/tex]
or
[tex]\eta=30\%[/tex]
So, the efficiency of each cycle of a heat engine is 30 %. Hence, this is the required solution.