Word Problem

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 hit the ground?

Answer 1

I will outline the procedure for you and you can take it from there.

The height of the ball as a function of time is

h(t) = -16t² + 64t

When it reaches the ground, h(t) = 0.

0 = -16t² + 64t

Solve the quadratic for t. You will get two solutions.  One of them is t=0, which is the moment when the ball was hit while on the ground.  The other solution will be t>0, which is time elapsed from when the ball was hit and it reached the ground again.