Step-by-step explanation:
initial speed = 272 ft/s
h = -16t² + 272t
a. 1120 = -16t² + 272t we change a bit into
16t² - 272t + 1120 = 0 then divide all with factor 16
t² - 17t + 70 = 0
(t - 10)(t - 7) = 0
t = 10 and t = 7
7 s when it goes up and 10 sec when the rocket goes down.
b. 1152 = -16t² + 272t we change a bit into
16t² - 272t + 1152 = 0 then divide all with factor 16
t² - 17t + 72 = 0
(t - 9)(t - 8) = 0
t = 9 and t = 8 sec
c. since the answer of a and b is:
7 sec and 8 sec the rocket goes up but at 9 sec and 10 sec the rocket goes down then we can take conclusion that the maximum height is reached at 8.5 s
so how long the rocket in the air?
goes up : 8.5 sec
goes down : 8.5 sec
total = 17 sec
