Question

If an object is dropped from a height of 144 ft, the function h(t) = –16t² + 144 gives the height of the object after t seconds. When will the object hit the ground?
(1 point)

A) 1.5 s

B) 3 s

C) 6 s

D) 9 s

Answer 1

To find when the object will hit the ground, we need to set h(t) = 0 and solve for t.

-16t² + 144 = 0

Divide both sides by -16:
t² - 9 = 0

Factor the equation:
(t - 3)(t + 3) = 0

Set each factor equal to zero and solve for t:
t - 3 = 0 --> t = 3
t + 3 = 0 --> t = -3

Since time cannot be negative in this context, the object will hit the ground at t = 3 seconds.

The answer is B) 3 s.