# Work done on the block by force

## Homework Statement

A block is pushed across a rough horizontal surface from point A to point B by a force (magnitude P = 5.4 N) as shown in the figure. The magnitude of the force of friction acting on the block between A and B is 1.2 N and points A and B are 0.5 m apart. If the kinetic energies of the block at A and B are 4.0 J and 5.6 J, respectively, how much work is done on the block by the force P
between A and B?

W= PCos (theta)D

## The Attempt at a Solution

I have no idea what to do for this!

I suppose Work done on the block = change in kinetic energy + work against friction

tiny-tim
Homework Helper
Welcome to PF!

Hi Zmuffinz! Welcome to PF!

(have a theta: θ )
W= PCos (theta)D

I have no idea what to do for this!

Well, what is θ in this case?

well you see thats why im stuck, i wasnt given an angle, or mass of the block or anything so ive got no clue as to what to do:(

I suppose Work done on the block = change in kinetic energy + work against friction

and how do i calculate work against friction?

Doc Al
Mentor
well you see thats why im stuck, i wasnt given an angle, or mass of the block or anything so ive got no clue as to what to do:(
You didn't post the diagram, but I presume that the force was applied horizontally. That will tell you all you need about angles.