(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Box A

Mass=3.2kg

Force of Friction=2 Newtons

Box B

Mass=2.1kg

Force of Friction=1 Newton

Force applied 10.5 Newtons [horizontally].

http://img162.imageshack.us/img162/7697/f1qd1.png [Broken]

Q. Find the magnitude of the force of contact between the two boxes.

2. Relevant equations

F=ma

3. The attempt at a solution

I need to find acceleration first since the Force of Friction of both boxes is not greater than the Force Applied.

Fnet=(mA+mB)a

(mA+mB)a=Fa-(FfA+FfB)

(3.2kg+2.1kg)a=10.5N-(2N+1N)

(5.3kg)a=10.5N-(3N)

a=10.5N-(3N)/5.3kg

a=7.5N/5.3kg

a=1.415m/s/s

Now, I tired many, many methods of solving for this from here on, including the example from this page:https://www.physicsforums.com/showthread.php?t=202002

However, the result seems still to be wrong.

I got 7.5N as the internal force both boxes act upon eachother.

Any help is appreciated although not dire.

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# Homework Help: 2 boxes with 1 applied force

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