Answer Happy

Please help with last part!
A ball is dropped at t=0 from rest 2.80 m directly above the vertex of a concave spherical mirror that has a radius of curvature of magnitude 1.25 m and lies in a horizontal plane. (a) Describe the motion of the ball's image in the mirror. (b) At what instant or instants do the ball and its image coincide? Part 1 of 7 - Conceptualize: The diagram below shows the physical arrangement in the problem. The ball is at an initial position yi​=h above the mirror, the vertex of which is at position y=0. The mirror has radius of curvature Rr​ and we'll use f for the focal length
t=g2(h−R)​​ 5