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!