# Help with a problem?

1. Nov 1, 2008

### choyphin

1. The problem statement, all variables and given/known data
After a bobsled race, the sled and riders have been partially slowed down up in an icy incline, but they need to be brought to a stop. This happens on a portion of track inclined at 30 degrees that has a coefficient of kinetic friction of 0.60. The sled enters the incline at 25.0 m/s. How far does it travel along the incline before stopping?

2. Relevant equations
Ff=UFn
Fn=mgcosO
f=ma

3. The attempt at a solution
I couldn't find a way of doing it, since the , mass isn't given, maybe i'm overlooking something?

2. Nov 1, 2008

### HallsofIvy

Staff Emeritus
Take any mass you like, say 100 kg. It should cancel out in the end.

3. Nov 1, 2008

### choyphin

how would you set up the equation? and also im sort of clueless on how to find how far the sled goes... sorry.

Last edited: Nov 1, 2008
4. Nov 1, 2008

### choyphin

I got as far as finding the resultant force for the vectors, which i got was 2000N, but that's as far as i got.

5. Nov 1, 2008

### HallsofIvy

Staff Emeritus
I think I would be inclined to use energy rather than force.

6. Nov 1, 2008

### choyphin

ok so using the formula 1/2vi^2=FG(cos 30) d
and solving for D, in which i got 88.28, would that be correct?

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook