(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A baseball pitcher throws a ball vertically upward and catches it at the same level 4.2s later

a) with what velocity did the pitcher throw the ball?

2. Relevant equations

3. The attempt at a solution

I put this into givens

t = 4.2 s

displacement = 0 m if the ball goes up and then comes back at the same level I figured it has a displacement of 0

acceleration = -9.81 m/s

Vf = 0 m/s since it goes up then reaches a climax and it was already thrown with an initial velocity that you are trying to find

so I decided to use the vf = vi + a(t)

so.. then I rearranged it so that it was

vf - ( a ) ( t ) = vi

which gave me

-(-9.81)(4.2) = vi

and then I got 41.2 but thats not the right answer :S so im not sure if its just that im using a wrong equation or that I have the wrong givens I don't know exactly what im doing wrong please point me in the right direction.

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# Homework Help: Calculations involving freefall

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