# Homework Help: Newtons laws problem

1. Oct 9, 2011

### Omnomnomnom

1. The problem statement, all variables and given/known data
what is the coefficient of friction between a 41N bookcase and the groud, when the bookcase accelerates at .25m/s2?

2. Relevant equations

F=ma Forcefriction=μ*force normal

3. The attempt at a solution
a=.25 m=41 μ=? I have absolutly no idea what i am doing

2. Oct 9, 2011

### WJSwanson

The problem statement appears to be incomplete. Is the bookcase sliding down a slope? Were you given a coefficient of friction?

3. Oct 9, 2011

### Omnomnomnom

I have to find the coefficient of friction between the bookcase and the ground, this is all that I was given, there is no angle. I am assuming that this is a flat surface.

4. Oct 9, 2011

### WJSwanson

Are you told the force that's being applied to move the bookcase horizontally? Because I really can't think of any method to find the coefficient of friction between two surfaces just with the normal force (weight in Newtons, for a flat surface with no external vertical forces acting) and relative acceleration between the surfaces.

5. Oct 9, 2011

### Omnomnomnom

the problem up above is all that I have, oh well my teacher has given us impossible problems before maybe this is another >.<

6. Oct 9, 2011

### WJSwanson

That strikes me as rather odd. I mean you could attempt to find a general solution for $\mu$ in terms of the data you have. Since you have a gravitational force (which equals the normal force) and can use it to derive the mass of the bookcase, that allows you to calculate that the net force on the object is m * anet = m * (aapplied force - $\mu$g * â)

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