Question

You get bored one day and launch a rocket straight up in the air in your back yard at 80ft/sec . zit turns out the equation h(t)=-16t^2 +80t represents the height of the rocket after t seconds.

a) What is the height of the rocket after 1,2,3,4 seconds?
(1=64 2=96 3=96 4=64)

b) When will the rocket be 80feet in the air?

c) the rocket launches at 80ft/sec . why is the answer to (b) not 1 second

d) when does the rocket hit the ground?
(is it 5sec?)
e) what is the maximum height of the rocket?
(is it 100ft at 2.5sec?)

f) graph h(t)=-16t^2+80t

Answer 1

are you asking for the answers/explaination to b through f?

Answer 2

yeah, im stuck on how to do those

Answer 3

well considering that the equation that is given to us the "h(t)" part is the height that is acheived at a certain time

Answer 4

You can us the height that is given to you to plug into the equation and solve for t to get the possible time(s)

Answer 5

well that being the way to solve B

Answer 6

so
80=-16t^2+80t ?

Answer 7

yeah then just solve for t

Answer 8

so
-16t^2+80t-80 ?
but i cant get it to come out with the right answer
sorry about all this DX

Answer 9

you seem to be on the right track, notice though that you can simplify the equation by dividing the whole equation that you have now by a certain number

Answer 10

Oh and no worries Im glad to help

Answer 11

divide by -16 so
t^2 -5t +5

do i factor now?

Answer 12

yes or use the quadratic equation if you cant factor

Answer 13

thank you! i got 1.38 and 3.61 which both get me 80ft

Answer 14

No problem however you have to figure out which one is the right one, or if both can be the right time

Answer 15

i believe both should be right, as the rocket will be at 80ft twice, going up then coming down