# Tension of string holding one mass to a wall, on top of another moving mass?

1. Mar 15, 2009

### finniusmorgan

Hello!
This is my first post, I am taking an introductory physics course during my second semester of college and having some trouble with this problem. I hope I have followed the correct format, I appreciate any help that can be offered!

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

A 4.82 kg block is placed on top of a 10.7 kg
block. A horizontal force of F = 69.7 N is
applied to the 10.7 kg block, and the 4.82 kg
block is tied to the wall. The coefficient of
kinetic friction between all moving surfaces
is 0.197. There is friction both between the
masses and between the 10.7 kg block and the
ground.
The acceleration of gravity is 9.8 m/s2 .

2. Relevant equations

F=ma
f= [coefficient of friction]*Fn

3. The attempt at a solution

I really don't know how to find the normal forces that are used in finding the frictional force, but after that I would subtract the friction from the horizontal force to find the net force on the bottom (10.7kg) object, but I do not understand how to relate that to the tension in the string holding the second object.

Thank you!

2. Mar 16, 2009

### sArGe99

Hint : The frictional force between the blocks acts in different directions for the bodies. Tension can be calculated from it..