Question

It is said that work done by a machine is always less than the works done the machine, then what is the use of the machine?

Answer 1

First, the work done by a machine is always less than the work done on machine as some energy (work) is lost in overcoming friction between the moving parts or weight of machine.
Second, A machine is used to
1)Change the direction of applied force(effort) to convenient direction
2)Change the point of application of force(effort) to a convenient point (check the example of pedal in bicycle for further understanding)
3)Acting as force multiplier
4)Acting as speed multiplier