1. Sep 11, 2009

### briteliner

1. The problem statement, all variables and given/known data

Start from this equation: E=(1/2)mvr^2+U(r)

and solve for dt. Set up the integral to find the relation between r and t, then carry out the integral in the special case that E=0.

2. Relevant equations

3. The attempt at a solution
HOW DO I GET DT? DO I HAVE TO TAKE THE DERIVATIVE OF THIS? IF SO, WITH RESPECT TO WHAT?

THANKS!

2. Sep 11, 2009

### rootX

t is time, and I assume you are trying to prove that energy remains constant using vector calculus. v = dr/dt.

3. Sep 11, 2009

### briteliner

i understand that dt is time, but now how to get dt.

4. Sep 11, 2009

### rootX

I told you v = dr/dt.

I never went through all of this derivation, but I think that's the only dt there.