# Pushing blocks

1. Oct 6, 2005

### brad sue

Hi ,

please help me with this question

We have 3 blocks on an horizontal surface (frictionless). We apply a force F=8N
What are the forces on each 3 blocks.

My solution:

For the block 1 I found: m1g(down), Normal reaction R1 ( up), R2/1 (left)
Here is there an R1/2 (right) force of block 1 on the force F=8N?

Block 2: m2g( down), normal reaction R2(up), R3/2, R1/2

Block3: m3g (down), normal reaction R3(up), R2/3,R3/2

My problem is about the reaction between blocks
I am not sure about that. Can someone help me Please

Thank you

2. Oct 6, 2005

### siddharth

Whenever, you are solving problems of this type, the first thing you should do is draw a Free Body Force Diagram. In this case, draw each of the blocks and the forces acting on the blocks.

When you are drawing the Free Body diagram, take care to mark only the forces which are acting ON the body (in this case block) and not due to the body.

For example, in Block 3, the forces acting on the block will be mg, normal reaction(R3) and R2/3 only. The force which the 3rd block exerts on the second block(R3/2) should not be drawn in the Free Body diagram of Block 3

Last edited: Oct 6, 2005
3. Oct 6, 2005

### brad sue

Thanks a lot I am gonna do to it!

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