# Coefficient of Kinetic friction

1. Nov 29, 2004

### Tabe

Ok, in this problem, I am given theta, which in 30 degrees, and acceleration, which is 1.2 m/s^2. How do I solve for the coefficient of Kinetic friction without the mass?

2. Nov 29, 2004

### Gokul43201

Staff Emeritus
You have not described what the problem is about...so it's hard to help really. Can you write down the question as you have it ? And in addition, post whatever thoughts/ideas you have.

3. Nov 29, 2004

### Tabe

The problem is: A box slides down a 30 degree ramp with an acceleration of 1.2 ms/^2. Determine the coefficient of kinetic friction between the box and the ramp. I have tried to solve the problem without the mass, but the formulas that I have all involve mass, or the forces. I don't know how to solve the problem with the variables that I am given for either of them.

4. Nov 29, 2004

### Justin Lazear

The mass doesn't matter.

Don't try to calculate numerical values for each individual step. You must either leave all of your equations in terms of m and you will find that mass drops out of your equation for Newton's Second Law, or you must make up a value of m and trust me that mass doesn't matter. Honestly, I wouldn't trust me if I were you.

--J

5. Nov 29, 2004

### 600burger

As Justin Said

Dont worry about the numbers. Solve with only symbols first. Its alot easier to solve and you can quicklly simplify it. After you think you've solved it go back and check your units (for this one all the units should cancel). Also, in future endevors (larger more complex problems) your life will be alot easier when it comes to finding mistakes/errors.

-Burg