Explanation :
The efficiency of a machine is always less than 100 %. This is because some of the energy gets lost in the form of heat energy, sound energy and frictional energy.
Mathematically it is defined as :
\(\eta=\dfrac{W_o}{W_i}\)
Where,
\(\eta\) is the efficiency
\(W_o\) is output work
\(W_i\) is input work
Hence, this is the required explanation.
