# Work Against Friction

1. Oct 9, 2007

### Darthsparerib

1. The problem statement, all variables and given/known data
You push an object of mass slowly, partway up a loop-the-loop track of radius , starting from the bottom, where the normal force to the track is vertically upward, and ending at a point a height above the bottom. The coefficient of friction between the object and the track is a constant .Find the work you do against friction.

2. Relevant equations Work against friction= Friction Force x Displacement

3. The attempt at a solution
Not how to get the height of the car. I belive that the friction part would simply be (Kinetic Friction)x(Normal Force). But I'm not entirely sure about how to get the normal force either

2. Oct 9, 2007

### Hootenanny

Staff Emeritus
Welcome to the forums Darth,

In what direction (relative to the surface) does the normal force act?

3. Oct 9, 2007

### Darthsparerib

I think that it acts towards the center of the loop

4. Oct 9, 2007

### learningphysics

Do they give any numbers or variables?

5. Oct 9, 2007

### Darthsparerib

No, no numbers are given

6. Oct 9, 2007

### Darthsparerib

the variables are m-mass Radius-R an ending point of h<R and the coefficient of friction is u

7. Oct 9, 2007

### learningphysics

Suppose theta is the angle the surface forms with the horizontal... what is the normal force in terms of theta. What is the frictional force?