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
Answer:
c
Step-by-step explanation:
Answer
at first I said 1/2 but it's 2/5's.
Step-by-step explanation:
Answer:
14d + 12c -4
Step-by-step explanation:
Let's start by imagining a rock being thrown to the air.
Let's say that going up is the positive direction and so, going down is the negative.
The acceleration is pointing down (because of gravity) so it's always negative. While the rock is going up, it's velocity/speed is positive, but the acceleration is negative.
While the rock is going down, both acceleration and speed are negative.
This shows that the first statemente is true, but the second is false.
You can also think that if you define going DOWN as the POSITIVE direction, you can have both positive acceleration and speed, or positive acceleration and negative speed.
