Question

If an object is dropped from the height of 54 feet,

the function h = -16t² + 54 gives the height of the object after
t seconds.
Approximately how long will it take before the object hits the ground?

a. 2.45
b. 1.84
c. 1.30
d. 0.75

Answer 1

b

Explanation:

When the object hits the ground , the h = 0 , that is

- 16t² + 54 = 0 ( subtract 54 from both sides )

- 16t² = - 54 ( divide both sides by - 16 )

t² =
`(54)/(16)` ( take square root of both sides )

t =
`\sqrt{(54)/(16) }` ≈ 1.84 seconds ( to 2 dec. places )