Question

What happens on the maximum height of verticals projectiles?

Answer 1

are u asking what happens when a projectile is fired vertically?

Answer 2

At maximum height the velocity in y-direction is 0m/s and the acceleration of gravity constantly acts (9.81m/s^2) and as for the x-direction, the velocity is constant since the beggining of the motion and the acceleration is 0m/s^2.