What is the efficiency of a pulley system that increases the potential energy of a load by 60J from an input of 100J?

The efficiency of a system is calculated by comparing the useful output energy to the input energy, expressed as a percentage. In this scenario, the useful output energy is the increase in potential energy of the load, which is 60J, while the input energy provided to the system is 100J.

To calculate the efficiency, you would use the formula:

Efficiency = (Useful Output Energy / Input Energy) × 100%

Substituting in the given values:

Efficiency = (60J / 100J) × 100% = 60%

This calculation shows that the pulley system converts 60% of the input energy into useful work, which is the potential energy gained by the load. This indicates that 60% of the energy input is effectively used in lifting the load, meaning the answer directly aligns with the definition of efficiency in a mechanical system.