# Roller coaster physics

1. Apr 28, 2008

### Jason03

Im trying to figure when you have a rollercoaster or train, how are the forces different at the top of tracks compared to the bottom of the tracks.

How does this relate to setting up F=MA....and the Normal Force.

I know at the top you would have a feeling of weightlessness and at the bottom you are pushed into your seat greatly.

Thanks

2. Apr 28, 2008

### Dick

It doesn't relate to any real forces, it relates to the acceleration of the rider. At the top his acceleration is down, at the bottom it's up. The normal force has to balance both gravity and the acceleration of the rider.

3. Apr 28, 2008

### Jason03

ok, im setting up a problem that asks for the force exerted on the seat of an 80 kg person. At the top, and at the bottom

So I am using this equ. ( i have r,v, m and g)

F=MA

N-mg = m (v^2/r)

so what would differ for the top and bottom?

4. Apr 28, 2008

### Dick

The direction of the v^2/r. It's directed towards the center of rotation. At the top, it's down. At the bottom, it's up. You have to keep track of the direction of v^2/r by hand.

5. Apr 28, 2008

### Jason03

ok thanks....i will give that a try