# Applied force on two blocks on a horizontal frictional plane

1. Oct 13, 2009

### lilaznjewel

1. The problem statement, all variables and given/known data
Two blocks connected by a string are pulled
across a rough horizontal surface by a force
applied to one of the blocks.
The acceleration of gravity is 9.8 m/s2 .
1st block = 2 kg
2nd block = 8 kg
Force on second block at 52◦
μ = 0.29

[ 2kg ]-------[ 8kg ]/ 52 degrees

If each block has an acceleration of 1.6 m/s2
to the right, what is the magnitude of the
applied force? Answer in units of N.

2. Relevant equations

3. The attempt at a solution

What I got was 72.15 N but I got it wrong and I have no idea what I did wrong

Last edited: Oct 13, 2009
2. Oct 13, 2009

### Jebus_Chris

Draw a fbd and sum the forces for each block in the x and y.

3. Oct 13, 2009

### lilaznjewel

what do i use for the force against friction for the block being pulled?

4. Oct 13, 2009

### Jebus_Chris

You need to find an expression for the normal force. In the y direction the force of gravity acts downward, the normal force acts upward, and the applied force acts upward.

5. Oct 13, 2009

### lilaznjewel

ok for the 8kg block i got 39.30N the problem that i am having for the 2kg block is that i do not no what Force I am solving for that is pulling the block is it Fcos60 like the previous one or is it the tension of the string

6. Oct 13, 2009

### Jebus_Chris

The tension in the string is pulling the second block.

7. Oct 13, 2009

### lilaznjewel

would you find that simply by multiplying mass times acceleration of the 2kg block?

Last edited: Oct 13, 2009