Denis throws a ball downward at an initial speed of 15 m/s from the top of a cliff. (a)
what is the speed and velocity of the ball 8 seconds later? (b) How far does it travel
during this time and what is the displacement?

Multiply the time by the acceleration due to gravity to find the velocity when the object hits the ground. If it takes 9.9 seconds for the object to hit the ground, its velocity is (1.01 s)*(9.8 m/s^2), or 9.9 m/s.

Explanation:really sorry if it wrong,i mean reall

it is called kinetic energy