# Homework Help: Girl Riding down hill (Friction)

1. Nov 6, 2009

### DLPhysics

1. The problem statement, all variables and given/known data
A girl coasts down a hill on a sled, reaching level ground at the bottom with a speed of 6.2 m/s. The coefficient of kinetic friction between the sled’s runners and the hard, icy snow is 0.059, and the girl and sled together weigh 736 N.The acceleration of gravity is 9.81 m/s2 .
How far does the sled travel on the level ground before coming to a rest?

2. Relevant equations
Vf^2 = Vi^2 + 2ax

Ffr (force friction) = Coefficient of friction * Fn (normal force)

3. The attempt at a solution
I'm thinking that I have to find the acceleration of the girl and the sled, but I don't think that I am given enough information necessary to solve for that. I just do not know how to approach the problem.

2. Nov 7, 2009

### rootX

What kind of forces are involved that affect her motion?

What exactly you think you are not given?

3. Nov 7, 2009

### DLPhysics

I think that I need the angle of the hill she is sliding down to find out the acceleration because I certainly think that she is sliding down the hill, and I know that friction affects her motion.

4. Nov 8, 2009

### DLPhysics

I also know that there is acceleration involved at some point, but I don't know how long it took her to decelerate from 6.2 m/s to 0 m/s. I'm REALLY FRUSTRATED at this point because whenever I setup Force and Kinematic equations, I'm always missing TWO variables. I would like someone to HELP me. The problem, I think, fails to give me enough information.............

Damion (sorry for the rant!)

5. Nov 8, 2009

### DLPhysics

Fg acts down on the sled while Fn keeps the sled on the ground. Ffr acts to the right because I assume she is moving to the left. However, is the hill at an angle? I think it is, but if it is, I don't know how to find the angle. PLEASE, SOMEBODY HELP!!!