# How to find acceleration given only angle of slope and coefficient of friction?

1. Sep 24, 2012

### ExtendedG

1. The problem statement, all variables and given/known data
A crate is placed on an inclined board. The coefficient of friction between the crate and the board is 0.26 , and the angle of the slope is 16 degrees. Calculate the acceleration of the crate down the incline.

2. Relevant equations
F=ma
Ff=umgcos(theta)
Forge of gravity parallel = mgsin(theta)

3. The attempt at a solution
F=ma
Fg - Ff = ma
mgsin(theta) - umgcos(theta) = ma
so this is where it gets tricky for me.. i've tried factoring and removing a mass from each side.. but i'm still left with one mass.
What do i do? :/

2. Sep 24, 2012

### rock.freak667

From here:

mgsinθ - umgcosθ = ma

your mass 'm' cancels out, so the acceleration does not depend on the mass.

3. Sep 24, 2012

### ExtendedG

sorry I'm still confused, but which mass comes out? or all the masses cancel out? when i try that, I don't get the answer.

4. Sep 24, 2012

### rock.freak667

All of the 'm's in the equation are the same, so they all cancel out.

5. Sep 24, 2012

### ExtendedG

Ah true okay thank you sir, help very much appreciated, so then I would just do:

gsinθ - ugcosθ = a

Now does the equation above work? because I think I remember trying this cancelling out all of the m's, and I got a wrong answer, but I probably did my math wrong. I'll check once I finish with my chemistry and math homework.