A perfectly efficient machine converts all the power applied to it into outputted force. Efficiency is a measure of how effectively a machine converts input energy or power into useful output work. In the case of a perfectly efficient machine, there are no energy losses, and all the power supplied to the machine is fully utilized to generate the desired output force or work.

In reality, no machine can achieve 100% efficiency due to various factors such as friction, heat losses, and other energy dissipations. However, the concept of a perfectly efficient machine is used as a theoretical benchmark to understand the ideal performance of a machine when no energy is wasted or lost during the conversion process.