Question

A 51-kg packing crate is pulled with constant speed across a rough floor with a rope that is at an angle of 37.0° above the horizontal. If the tension in the rope is 115 N, how much work is done on the crate to move it 7.0 m?

Answer 1

work is done by the pulling force which is same as the tension force in the rope. the net work done is zero for the crate since crate moves at constant velocity. but there is work done by the tension force which is equal in magnitude to the work done by the frictional force.

T = tension force in the rope = 115 N

d = displacement of the crate = 7.0 m

θ = angle between the direction of tension force and displacement = 37 deg

work done on the crate is given as

W = F d Cosθ

inserting the values given above

W = (115) (7.0) Cos37

W = 643 J