The ball hits the ground at unknown time (t) when the height (h) = 0
h(t) = -16t² + vt + h ⇒ v = 64, h = 0, h(t) = 0, find t
0 = -16t² + 64t
0 = -16t(t - 4)
0 = -16t or 0 = t - 4
t = 0 or t = 4
It starts at t = 0 seconds and ends at t = 4 seconds
Answer: B
