Chapter 11 QuaDraTiC appliCaTionS 411t^2 =^32
16
t^2 = 2
t = 2 (t = – 2 is not a solution)
t ≈ 1.41The object will reach a height of 28 feet after about 1.41 seconds.PRACTICE- A ball is dropped from a height of 50 feet. How long after it is dropped
will it reach a height of 18 feet? - A small object falls from a height of 200 feet. How long will it take to
reach a height of 88 feet? - A small object is dropped from a 10th floor window (at a height of 110
feet). How long will it take for the object to pass the 3rd floor window
(at a height of 35 feet)? - An object is dropped from 120 feet. How long will it take for the object
to have fallen from 100 feet? (Hint: the height the object has reached
after it has fallen 100 feet is 120 – 100 = 20 feet.)
✔SOLUTIONS
Negative values of t will not be solutions.
- In the formula h = −16t^2 + v 0 t + h 0 , h 0 = 50 and v 0 = 0.
h = −16t^2 + 50
We want to find t when h = 18.18 16 50
16 32
32
16
2
2
12
2
22 .= –+
=
= =
=
≈ t
t
tt
t
t 441The ball reaches a height of 18 feet about 1.41 seconds after it is
dropped.PRACTICE- A ball is dropped from a height of 50 feet. How long after it is dropped
will it reach a height of 18 feet?
PRACTICE- A ball is dropped from a height of 50 feet. How long after it is dropped