I'm having trouble with this problem, I think I solved it but I don't know if what I did is right...
At first when the velocity is 0 and the spring is at its natural length, there's just gravitational potential energy, so $$E_i=mgh$$
And then, when the mass is released and then reaches its...
The first thing I did, was to find the equations for player A (p) and ball's (b) path (for each i and j component I used the equation I wrote in the relevant equations) and then I found the derivative of both equations so I could have the velocity:
$$\vec{r}_p(t)=(6t^2+3t)\hat{i}+20\hat{j}...