Question

Determine the efficiency of the following simple machine operating at an unknown efficiency. An applied effort of 244 N is required to lift a 76 kg load 3.35 m upwards, while the effort travels a distance of 11.85 m.

Answer 1

Efficiency = (useful output work) / (input work).

Output = m g h = 76 kg × 9.8 m/s² × 3.35 m = 2.495 × 10^3 J.
Input = effort × distance = 244 N × 11.85 m = 2.8914 × 10^3 J.

Efficiency = 2495.08 / 2891.4 ≈ 0.8629 = 86.3%.