Bill does 1500 J of work on a lever, which is a simple machine. The lever does 1350 J of work on a stone.

What is the efficiency of the lever?

0.9%

1.1%

90%

111%

Efficiency is the measure of how much work or energy is conserved in a process. In many processes, work or energy is lost, for example as waste heat or vibration. The efficiency is the energy output, divided by the energy input, and expressed as a percentage.

Efficiency is the energy output, divided by the energy input, and expressed as a percentage.

Efficiency = (1350/1500) * 100

= 90%