# Properties of Friction

1. Feb 15, 2010

### Matt12345

1. The problem statement, all variables and given/known data
Body A weighs 110 N, and body B weighs 37 N. The coefficients of friction between A and the incline are μs = 0.56 and μk = 0.25. Angle θ is 40°. Let the positive direction of an x axis be up the incline.

(a). Find the acceleration of A if A is initially at rest.
(........ m/s^2) i

(b). Find the acceleration of A if A is moving up the incline.
(.........m/s^2) i

(c). Find the acceleration of A if A is moving down the incline.
(.........m/s^2) i

2. Relevant equations
F=ma

3. The attempt at a solution
So I am not really sure how to solve this problem at all. I have tried a few ways, none have come up with reasonable or correct answers.

I tried using...

FT = mA * g * sin(theta) - fk

where fk = mewk * FN
and setting FN = g * a

I then solved for a and came out with 134 but that was wrong and didn't make sense.

I have no idea what to do next. Can anyone help me out? That would be awsome.

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2. Feb 15, 2010

### Matt12345

So I got part (a). which is 0. I don't know why I didn't try that before. I feel stupid. But parts (b). and (c). I am still not sure about.

3. Feb 16, 2010

### PhanthomJay

This problem makes no sense. Either the block A is at rest, or it moves up the plane, or moves down the plane. It can't do all three!