# Work done on the block by force

1. Jul 23, 2009

### Zmuffinz

1. The problem statement, all variables and given/known data

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?

2. Relevant equations
W= PCos (theta)D

3. The attempt at a solution
I have no idea what to do for this!

2. Jul 23, 2009

### songoku

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

3. Jul 23, 2009

### tiny-tim

Welcome to PF!

Hi Zmuffinz! Welcome to PF!

(have a theta: θ )
Well, what is θ in this case?

4. Jul 25, 2009

### Zmuffinz

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:(

5. Jul 25, 2009

### Zmuffinz

and how do i calculate work against friction?

6. Jul 25, 2009

### Staff: Mentor

You didn't post the diagram, but I presume that the force was applied horizontally. That will tell you all you need about angles.