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Calculating Final Velocity

by maca_404
Tags: final, velocity
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Mar5-08, 05:40 AM
P: 7
Question is a golf ball is dropped from a height of 78m assuming gravity is 9.8 m s, What is the velocity of the ball after the first 10m.

I assume the equation to use is [tex]v^2=u^2+2ax[/tex]

v = Final velocity
u = Initial Velocity
a = Acceleration
x = Displacement

So I plug in [tex]v^2 = 0+2(9.8ms)(10.0)[/tex]

Now according to the answer sheet V should be 14.0 m s but no matter how I plug this in I cant seem to get the right answer.

I think the problem is the way I am actually doing the math so if someone could perhaps step threw the maths so I can see where I went wrong.

Thanks for any help
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
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Mar5-08, 05:48 AM
P: 364
you shoudnt only learn about plugging values into the formula, you should learn the physical meaning of the formula!!!!!!!!!! THAT IS VERY IMPORTANT I got 14 using the EXACT equation above, I believe you have made a careless mistake.
Mar5-08, 05:48 AM
Sci Advisor
PF Gold
P: 39,363
No, no one can possibly tell you what you did wrong, because you haven't told us what you did! The equation you have, v2= 2*9.8*10 is correct and gives v= 14 m/s. Apparently you made a mistake in the arithmetic, although it seems rather elementary to me! Since you didn't show what you did or tell us what answers you got, I can't tell if it was something as simple as forgetting to take the square root.

Mar5-08, 05:53 AM
P: 7
Calculating Final Velocity

How embarrassing, oerg you where spot on I forgot to take the square of the answer I think I have been working at this too long tonight .

Thanks Again

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