# Kinetic Friction H E L P ! ! !

1. Oct 6, 2004

### songokou77

When mass M is at the position shown, it is sliding down the inclined part of a slide at a speed of 1.89 m/s. The mass stops a distance S2 = 1.85 m along the level part of the slide. The distance S1 = 1.25 m and the angle theta = 37.7 degrees. Calculate the coefficient of kinetic friction for the mass on the surface.

Well i kinda found a formula for this by changing the conservatiion of energy(K_f+U_f=K_i+U_i+W_nc).

The formula is mu_k=(-1/2*(V_i^2)-1/2*(g*h))/(g*S_total),

But I still dont get the right answer am I doing something wrong?

2. Oct 6, 2004

### arildno

Think again:
You haven't used the information that you are on an INCLINED plane!!

3. Oct 6, 2004

### songokou77

I used the incline plane to figure out h=Ssin37.7=0.26

4. Oct 6, 2004

### arildno

It's still wrong, you've used a frictional force: $$\mu{mg}$$
This is incorrect.
In addition, your signs are messed up