Question

A block A,weighing 100 N,is pulled up a slope of length 5 m by means of a constant force F(=100 N) as illustrated in the figure.

(a) What is the work done by the force F in moving the block A,5 m along the slope?

(b) What is the increase in potential energy of the block A?

(c) Account for the difference in the work done by the force and the increase in potential energy of the block.

Answer 1

Given: weight of the block = mg = 100 N and force = 100 N.
(a) Work done by the force in moving block 5m along the slope,
W = Force × Displacement
= 100 × 5 = 500 J
(b) Increase in potential energy of block A = mgh = 100 × 3 = 300 J
(c) Difference = (500-300)J = 200 J, which is used against friction.