Posted by **Jay Kay** on Friday, November 5, 2010 at 4:05pm.

A rock is thrown from on a cliff with the velocity of 15 m/s at an angle of 30 degrees. it takes the rock 6.30 seconds to hit the ground. how high was the cliff?

- Physics -
**bobpursley**, Friday, November 5, 2010 at 4:06pm
hfinal=hinitial+Vi*t-4.9t^2

you have hfinal=0, t, Vi=15sin30, solve for hinitial

- Physics -
**Jay Kay**, Friday, November 5, 2010 at 4:13pm
Where does the 4.9 come from though?

- Physics -
**bobpursley**, Friday, November 5, 2010 at 4:15pm
1/2 g= 4.9

- Physics -
**Jay Kay**, Friday, November 5, 2010 at 4:16pm
Oh, is it .5 multiplied by the acceleration of gravity?

- Physics -
**bobpursley**, Friday, November 5, 2010 at 4:17pm
yes.

- Physics -
**Jay Kay**, Friday, November 5, 2010 at 4:18pm
Alright. Thank you so much for your help!

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