Question

The formula: h = -1/2gt^2 + v0t + ho for the height of an object under the force of gravity, with g = 32 ft/sec^2 or 9.8 m/sec^2

A toy rocket is launched upward from a 2-meter platform with an intitial velocity of 100 m/sec.

a) give an equation for the height of the rocket after t secs
b) find the height of the rocket after 2 seconds. Round to nearest meter.
c) how long will it take for the rocket to hit the ground? Round to nearest tenth of a second.

Answer 1

HI! again

Answer 2

Hi! Sorry, I have a lot of problems after missing a adv. algebra class.

Answer 3

what is a adv algebra?

Answer 4

advanced algebra? (:

Answer 5

nvm in any case here is what you have
\[h_0=2,v_0=100, g=9.8\] so
\[g(t)=-4.9t^2+100t+2\]

Answer 6

you okay from there?

Answer 7

Um....

Answer 8

We are on part a right?

Answer 9

lol i take that as a "NO" ok yes, that was part 1

Answer 10

gotcha! So... using that equation we can figure out part b? But how?

Answer 11

\[g(t)=-4.9t^2+100t+2\\
g(2)=-4.9\times 2^2+100\times 2+2\]

Answer 12

i would use a calculator myself

Answer 13

So i multiply to get the height after two seconds?

Answer 14

you substitute 2 for t, i.e. evaluate the function at 2

Answer 15

so 221.6?

Answer 16

meters?

Answer 17

@misty1212

Answer 18

hold on let me check

Answer 19

i don't get that, i get this
http://www.wolframalpha.com/input/?i=-4.9*4%2B200%2B2

Answer 20

Gotcha! How about part c now? How long will it take to hit the ground?

Answer 21

@misty1212

Answer 22

when it hits the ground, the height is zero

Answer 23

solve \[g(t)=-4.9t^2+100t+2=0\] for \(t\)

Answer 24

if it was me, i would cheat

Answer 25

lol cheat how?

Answer 26

http://www.wolframalpha.com/input/?i=-4.9t^2%2B100t%2B2%3D0

Answer 27

looks like about \(20.4\) or so

Answer 28

gotcha!

Answer 29

THANKS SO MUCH!

Answer 30

\[\huge \color\magenta\heartsuit\]