# Homework Help: What are the two equations for Centripetal Force

1. Nov 3, 2012

### Interception

1. The problem statement, all variables and given/known dataI have to rearange both equations to find mass, radius, and velocity (each of them seperately).

2. Relevant equations I know that Centripetal Force= mass x (velocty^2/radius). In this case velocity is also equal to 2∏r/T (where T is the period), so I subsituted that in for v for the first equation and used it as the second. The experiment we did involved the period value, so I assumed that's what he wanted.

3. The attempt at a solution I was able to isolate the mass the just fine, it's when I try to find radius and velocity that complicate it. When I solve it for the second for radius however, I have r on both sides of the equation. For velocity, I just get the quantity 2∏r/T on one side with the rest on the other. It just looks messy to me. I was thinking for the radius issue, I could get rid of the r on the other side of the equation by making it 1/2(diameter)? I'm lost here. I'd appreciate some help.

2. Nov 3, 2012

### Staff: Mentor

Can you post those equations? It is hard to spot specific problems based on that description.

You want get equations of the type $v=...$ and $r=...$ from $F=m\frac{v^2}{r}$?