If a ball is thrown vertically upward with a velocity of 96 ft/s, then its height after t seconds is

Question

s = -16t^2 + 96t. What is the velocity of the ball when it is 128 ft above the ground on its way up?

Answer 1

well, v = at

so, what is t when

-16t^2 + 96t = 128?
Pick the lowest value, since you want the ball on its way up.

Now plug that in to find v at that time.