Question

What is the efficiency of a block and tackle if you pull 20 m of rope with a force of 600 N to raise 200kg piano 5 m?

Answer 1

W out = mass * distance * gravity

E in = Force * distance

Efficiency = W out / E in = (200 kg * 5m*9.8N) / (600N * 20m) = 0.81

0.81 x 100 = 81 %