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Rushin Naik

Feb 17, 2015

1. What is work done by a coolie walking on level road with load on his head? 2. Why is work done zero when, the direction of displacement and the direction of force on a body are perpendicular to each other?

1. What is work done by a coolie walking on level road with load on his head?
2. Why is work done zero when, the direction of displacement and the direction of force on a body are perpendicular to each other?

Answers(2)

Answer

Janhavi Govinda rao

1. Work done by a coolie, walking on level road with load on his head, on the load is zero.
2. 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

Amarnathreddy M

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 coolie 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 wor which is equal to the product of the force applied and the displacement.

He is moving the load on his head which alsready on his head so here is applying the force on the body to accelerate it. So the work done by him to move the load is equal to the change in the  load's kinetic energy ( here is no change in potential energy as the height of the object is not changed0
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