Calculating Work Against Friction in a Loop-the-Loop Track

[Darthsparerib]

Homework Statement

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.

Homework Equations

Work against friction= Friction Force x Displacement

The Attempt at a Solution

Not how to get the height of the car. I believe 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

 

[Hootenanny]

Welcome to the forums Darth,

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

 

[Darthsparerib]

I think that it acts towards the center of the loop

 

[learningphysics]

Do they give any numbers or variables?

 

[Darthsparerib]

No, no numbers are given

 

[Darthsparerib]

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

 

[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?