# Circular Motion and Gravitation HELP!

1. Jun 27, 2005

### kittn44

Hey there! Completely new here but thought someone could help. I have this problem where I don't even know where to start from.

The problem:

(Picture of loop with a man in a roller coaster cart hanging upside down from furthest top point of circle)

A man in the roller coaster is sitting on a bathroom scale. If he is traveling at 33.1 m/s at the point shown, the radius of the vertical coaster track is 61 meters, and the man has a mass of 55.3 kg, to the nearest newton, what does the scale read?

Ok, first off, the answer isn't something I'm concerned with anyway because these values will not be the same as the ones I end up having to work, so I really just need someone to explain HOW I do this and WHY. My class is only 5 weeks long and I'm taking too much in and I just don't grasp circular motion quite yet. Any ideas and help appreciated!

Also, if the man were at the most bottom point of the loop, would you work the problem differently?

THANKS

2. Jun 27, 2005

### Jameson

The acceleration for circular motion can be defined as:

$$a = \frac{v^2}{r}$$

where "a" is acceleration, "v" is velocity, and "r" is the radius.

Now once the acceleration is known, how might one find the force acting on the scale?