412 algebra De mystif ieD
- In the formula h = −16t^2 + v 0 t + h 0 , h 0 = 200 and v 0 = 0.
h = −16t^2 + 200
We want to find t when h = 88.
88 16 200
16 112
112
16
7
265
2
2
2
2
.= –+
=
=
=
≈ t
t
t
t
t
The object will reach a height of 88 feet after about 2.65 seconds.- In the formula h = −16t^2 + v 0 t + h 0 , h 0 = 110 and v 0 = 0.
h = −16t^2 + 110
We want to find t when h = 35.
35 16 110
16 75
75
16
75
16
2
2
2
2 .= –+
=
= =
≈ t
t
tt
t 117
The object will pass the third floor window after about 2.17 seconds.- In the formula h = −16t^2 + v 0 t + h 0 , h 0 = 120 and v 0 = 0.
h = −16t^2 + 120
The object has fallen 100 feet when the height is 120 – 100 = 20 feet, so
we want to find t when h = 20.
20 16 120
16 100
100
16
100
16
2
2
2= –+
=
= = =t
t
ttt
= 10
4
t . 25
The object will have fallen 100 feet 2.5 seconds after it is dropped.