# Homework Help: Friction Acceleration

1. Oct 13, 2008

### halo9909

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

A 219-kg crate is pushed horizontally with a force of 710 N. If the coefficient of friction is 0.20, calculate the acceleration of the crate.

m=219kg
force of friction= 219kg *.2 =43.8N?
2. Relevant equations

f=ma?
3. The attempt at a solution
I am not sure at all how to calculate the acceleration and what to use as the "F" to calcuate it

2. Oct 13, 2008

### aimslin22

friction is normal force*coefficient of friction

thus the force of friction would by 219*gravity*.2

The equation, F=ma, is right.

But friction always points in the opposite direction so it would set up like this:

Force(710) - friction = ma

then solve for a!

Hope this helps.

3. Oct 13, 2008

### halo9909

yeah that does help
since I didnt realize you had to subtract the 710 with the Ff

so 710-429.24=280.76N
280.76N/219=1.282
a=1.282m/s^2

4. Oct 13, 2008

### aimslin22

yup, I didn't do the actually calculations, but it looks right.
An easy way to remember this is :

winner force - loser force = ma

And free-body diagramming it helps too

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