Question

Given below is a few situations, study them and state in which of the given cases work is said to be done. Give reason for your answer. 

(a) A person pushing hard a huge rock but the rock does not move. 

(b) A bullock pulling a cart up to 1 km on road. 

(c) A girl pulling a trolley for about 2m distance. 

(d) A person standing with a heavy bag on his head. 

Answer 1

(a) Work done = 0, 

Reason- As the rock has not moved so displacement is zero. 

(b) Work done = Positive 

Reason – As the motion is in the direction of force applied. 

(c) Work done = Positive 

Reason – As the trolley is moving in the same direction in which force is applied. 

(d) Work done = 0 

Reason – As there is no movement in the position of the bag, therefore displacement is zero.