the videos ilusstrating for the problems are in good quality.
Although it is the matter of Calculus, I find it exciting and amusing. I spent 30 minutes thinking about this problem. I have never though about Mathematics applied in a bouncing ball. With a bouncing ball, people can find the motion equations: one of position, and the other of velocity. Moreover, it is a kind of applied Math in Physics problem: Falling the ball to find the position, velocity, and acceleration, right? I studied all these stuffs in high school, but they have been unreachable for me since then. Now, I understand a little bit. It is a good new, is it not???