Question

Can a machine have an efficiency of 100$\%$? Give a reason to support your answer.

Answer 1

The ratio of useful work done by the machine to the work put into the machine by effort is called efficiency of the machine.
$Efficiency=\frac{Workoutputonload}{Workinputbyeffort}$
$\eta =\frac{Workoutput}{Workinput}$$\times 100$
In practice no machine is perfect because some part of the work done on a machine is wasted in overcoming friction. Hence, the efficiency of the actual machine is always less than 1 (or less than 100 percent).