Question

A tennis ball is hit into the air and moves along an arc. Neglecting air resistance, where along the arc is the speed of the ball a)a minimum and b) a maximum?

I'm thinking it's at a max at the begging and end, and a min at the top, but that's just a guess.

Answer 1

Your guess is correct. Where potential energy is a maximum (at maximum height) the kinetic energy (and speed) must be a minimum. Where potential energy is a minium (a ground level) the kinetic energy (and speed) must be a maximum. If the ball went over a cliff, the speed would continue to increase until it hit the ground below.