# Homework Help: Circular Motion

1. Oct 21, 2007

### bww

A 1kg ball rolls along a circular track that is banked at 20 degrees. The normal force on the ball is 10.43N, tilted inward. The radius of the track is 10m.

a. What is the net force on the ball (include direction)?
b. How fast is the ball going for it to complete the turn?

and as for where i am, i don't really know where to start! to find the net force, i know i start with the 10.43N acting on it. I don't know if the 20 degrees comes into play at all or not. any help is greatly appreciated!

2. Oct 21, 2007

### mdk31

What I would recommend you do first is draw a free-body diagram and label all the forces.

3. Oct 21, 2007

### bww

yeah that was part of the question, i already did that part. i think i've got it right, but where to now?

4. Oct 21, 2007

### mdk31

Are you told to ignore friction? Are you given a coefficient of friction?

5. Oct 21, 2007

### bww

There is no friction, it is being ignored.

6. Oct 21, 2007

### mdk31

Okay, when I set up my free body diagram and chose my coordinate system, I got

x: F= -F[N]sin(20)=(-mv^2)/r

y: F= F[N]cos(20) - mg = 0

So, there is no net force in the y direction, it is all in the x direction.

mgtan(20)=(mv^2)/r

v=(rgtan(20))^(1/2)