Question

The height in feet of a golf ball hit into the air is given by `h= -16t^2 + 64t`, where t is the number of seconds elapsed since the ball was hit. How long does it take for the ball to reach the maximum height?

Answer 1

2 second

Explanation:

`h = - 16t^2 + 64t`.
The trajectory of the ball is a downward parabola passing by the origin. The ball reaches the maximum height at the parabola's vertex. On the coordinate grid (t, h),
t-coordinate of vertex:
`t = -b/(2a) = -64/-32 = 2` sec.
Answer: It takes 2 second for the ball to reach the max height h.