Velocity at the midway point

  • #1
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Homework Statement


The velocity at the midway point of a ball able to reach a height y when thrown with a velocity v0 at the origin is:


Homework Equations


v2=v02+2ay

The Attempt at a Solution


I made y = 1/2 y and the simplified the equation to v=sqrt(v02+ay)
But that is wrong because the answer is sqrt(v02/2)
Why?
 

Answers and Replies

  • #2
TSny
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See if you can continue to simplify your result. In particular, can you find a way to express ay in terms of v0?
 
  • #3
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a = (v-v0)/t
y = v0t+1/2 at2
Substituting those don't seem to help enough
 
  • #4
TSny
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In your first post, you stated the following useful equation: v2 = vo2 + 2ay.

In your problem, y represents the height to which the ball will reach (i.e., the maximum height). When the ball reaches maximum height, what can you say about the value of v on the left side of the equation?
 
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  • #5
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Oh wow, then you get ay = - v02/2
and then if you plug that back into my first equation, you get the answer.
Wouldn't have thought of that. Thanks!
 
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  • #6
Can you please explain more ?
 

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