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January 30, 2015

January 30, 2015

Posted by **Anonymous** on Friday, November 21, 2008 at 1:20pm.

I'm stuck on how to solve. I think I need to figure out how long the rock is in the air, which would be time it takes for the rock to arrive at the apex of the throw and then drop from the apex height to the ground. But since I dont know the initial velocity, how do I determine the height of the apex?

- Physics -
**drwls**, Friday, November 21, 2008 at 1:51pmThe horizontal distance away that it landed after T seconds tells you that

Vo cos 60 T = 15 , which leads to

T = 30/Vo

Also, the vertical velocity component Vo sin 60 is related to the total time T in the air by

Vo sin 60 T - (g/2) T^2 = -8.6

You have two equations in two unknowns.

Substitue 30/Vo for T in the last equation and solve for Vo

- Physics -
**Anonymous**, Friday, November 21, 2008 at 2:55pmthanks, I get it.

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