Question

After t seconds, a ball in the air from the ground level reaches a height of h feet given by the equation h= 144t-16t^2 . After how many seconds will the ball hit the ground before rebounding?

Answer 1

h=0
Therefore:
144t-16t²=0
t (144-16t)=0
We have two equations:
1)
t=0 (when the ball is released)
2)
144-16t=0
-16t=-144
t=-144 / -16=9 (this is the time )

Answer: the ball hit the ground in 9 s.