# Forces With Friction

1. Feb 21, 2010

### mcg5132

1. The problem statement, all variables and given/known data
A box of Cheerios (mass mC = 1.1 kg) and a box of Wheaties (mass mW = 2.9 kg) are accelerated across a horizontal surface by a horizontal force applied to the Cheerios box. The magnitude of the frictional force on the Cheerios box is 2.0 N, and the magnitude of the frictional force on the Wheaties box is 3.5 N. If the magnitude of F is 12 N, what is the magnitude of the force on the Wheaties box from the Cheerios box?

2. Relevant equations
Fs,max=UsFn
fk=UkFn
F=ma
Fn=mg

3. The attempt at a solution
I'm not entirely sure how to set up this equation, I know F= m1(Ff)-m2(Ff) ... ? Or something along those lines. I'm not sure where to begin really.

2. Feb 21, 2010

### kuruman

Draw a free body diagram of two-box system and put in all the forces that you know are there. Use Newton's Second Law to find the acceleration. Then draw a free body diagram of just the Wheaties box.