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April 19, 2014

April 19, 2014

Posted by **Brynn** on Sunday, September 23, 2012 at 10:51pm.

What is the height of the rock after 3 seconds?

How long will it take the rock to hit the bottom?

- algebra -
**Reiny**, Sunday, September 23, 2012 at 11:18pmYour equation should read

h(t) = -9.8t^2 + 100

when t = 3

h(3) = -9.8(9) + 100

= 11.8

it will be 11.8 m above the ground

how long to hit ground ??

when h(t) = 0

0 = -9.8t^2 + 100

9.8t^2 = 100

t^2 = 100/9.8 = 10.204..

t = √10.204.. = appr 3.2 seconds

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