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

Answer:

A. 3s

Step-by-step 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

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

$0 = -16t^2 + 144$

$16t^2 = 144$

$t^2 = \frac{144}{16}$

$t^2 = 9$

$t = \sqrt{9}$

$t = 3$

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