Q: A man of mass m, standing at the bottom of the staircase, of height L climbs it and stands at its top.
(a) Work done by all forces on man is equal to the rise in potential energy m g L
(b) Work done by all forces on man is zero
(c) Work done by the gravitational force on man is mgL
(d) The ratio force from a step does not do work because the point of application of the force does not move while the force exists
Ans: (b) & (d)