Question

A boy carries a load of 50 kg on his head and walk on a level road up to 100 m what is the work done by him

Answer 1

Remember the work done by an object and the work done on an object are not same they are diifferent from each other.


Case 1: if a boy walks on level road with load on his head he is moving himself and also he is moving the object.

So to move him self on the level road he is applying force on himself to displace him so here he is doing work which is equal to the product of the force applied and the displacement.

Work done = Force x displacement

W = F.s = Fs cos θ

where θ is the angle between the direction of force and the direction of displacement of the object. If they are perpendicular to each other θ = 90°. We have cos 90° = 0. Therefore
W = Fxsx0 = 0
Work Done = 0