Question

If an object is dropped from a height of 144 feet, the function h(t)=-16t^2+144 gives the height of the object after t seconds. When will the object hit the ground

A. 3s
B. 6s
C. 1.5 s
D. 9s

Answer 1

A. 3s

Explanation:

The height of the object after t seconds is given by:

`h(t) = -16t^2 + 144`

When will the object hit the ground?

It hits the ground after t seconds, and t is found when
`h(t) = 0`. So

`h(t) = -16t^2 + 144`

`0 = -16t^2 + 144`

`16t^2 = 144`

`t^2 = (144)/(16)`

`t^2 = 9`

`t = √(9)`

`t = 3`

3 seconds, so the correct answer is given by option a.