Can anyone help me out with this problem: A ball is thrown vertically upward with initial velocity v. Find the maximum height H of the ball as a function of v. Then find the initial velocity v required to achieve a height of H.

Question

anonymous · Answer

we'll just use the eq, $v^2 = u^2 +2aS$, since u=0, a=-g,(since it is opposite direction of v),
rearranging gives $S=\frac{v^2}{2g}$

anonymous · Answer

where S=H

anonymous · Answer

ive arrived at this answer too...however when i submitted it...it said that g was not defined in this context

anonymous · Answer

is there any way to answer this in terms of H and v only?

anonymous · Answer

or, you can just sub g=10 into it

anonymous · Answer

thats what i would think so too. but it still says that answer is incorrect

anonymous · Answer

oh oh. sorry. my mistake. it's initial velocity, not end velocity.
since v=0, $u=\sqrt{2gH}=\sqrt{19.8H}$

anonymous · Answer

tried that one too unfortunately....im not sure what they looking for

anonymous · Answer

dang==then i have no idea what they want

anonymous · Answer

thanks for trying to help though. ...its very much appreciated :)

anonymous · Answer

you're welcome :)