# Homework Help: Trajectory between two points

1. Dec 2, 2007

### issisoccer10

1. The problem statement, all variables and given/known data
How should you throw a super ball so that the trajectory of the ball moves back and forth between two points. The super ball undergos perfectly elastic collisions with the ground and does not slip. The moment of inertia for the super ball is I = 2/5*MR^2. Specify the initial velocity vector.

2. Relevant equations
m*velocity inital=m*velocity final

3. The attempt at a solution
Hate to say it but i'm totally stuck. I don't think it has to do with the path specifically, but i'm pretty lost in general. Any help would be greatly appreciated.

thanks

2. Dec 2, 2007

### dotman

Hello,

It appears (to me, at least) that there's not enough info here to say. Is this the whole problem? What two points do you want the ball to move back and forth between? How are they oriented? Where are they located in relation to the thrower?

3. Dec 2, 2007

### issisoccer10

the two points are some distance a part on a horizontal surface. Basically two points on the ground. It doesn't specify how far apart they are, but the trajectory is like a "loop" it could be an inverted parabola or a semicircle but it isn't specified. Also, we don't know from where or from how high the ball is thrown.