Question

what is the efficiency of a lawn mower's engine when the heat input is 1,000 joules and the waste heat is 750 joules

Answer 1

The answer would be 25%
Hope that helps

Answer 2

25%

Step-by-step explanation:

Efficiency of an engine is calculated by dividing the energy output over the energy input and expressing that as a percentage.

Efficiency =
x 100%

Given,

Heat input = 1000 J

Heat wasted = 750 J

Heat used = 1000 J – 750 J = 250 J

Efficiency =
`(250 J )/(1000 J)` x 100% = 25%