Here is the question I am trying to awnser:(adsbygoogle = window.adsbygoogle || []).push({});

A ball is thrown straight up and reaches a maximum height in 6.81 s.

What was the ball's initial speed?

Keeping in mind that we are not yet dealing with any sort of friction...

So for problems like this I do the following:

Given:

Xo - 0

X - ? (this might be zero I'm not sure)

Vo - ?

V - ? (this might be zero I'm not sure)

a - 9.8 m/s

t - 6.81 at it's maximum height

I need to solve for Vo. I'm not sure how to do this though.

I know I should use one of the equations of:

http://webphysics.iupui.edu/152/152F04/152Basics/kinematics/gif/kineq01.gif [Broken]

But I have no idea beyond that...

I tried the V=Vo + at with V as zero and t as 13.62 seconds (I doubled it beacuse I thought I should in order to get the complete time) and when I did that I got Vo as a negative...

And I know it's not a negative...

Any help???

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# Homework Help: Kinematics Question on thrown ball

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