# TBR Physics Section I Passage IV Question 25

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##### Full Member
10+ Year Member
TBR Physics Section I Passage IV Question 25....

Why would you use the formula, Vy^2 = Voy^2 +2adeltaY, to compare deltaY and Voy^2??

Why not use another formula relating velocity and deltaY.... such as Y = Yo + VoyT +1/2AT^2??? And say that velocity and deltaY are linearly related??

I have to be missing something here?!

Also, can provide a simple explanation that explains the difference between simple projectile motion (passage I) and this slingshot example (passage IV)? Im not getting this!

#### bullsfan1986

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15+ Year Member
in answer to your first question, you can't use the second equation you stated because it would compare vo and deltay as a function of time. You aren't given any value for time in the passage or the stem so you can't use that equation to make the comparison.

#### PingPongPro

##### Full Member
10+ Year Member
Kind of an old thread, but didn't see the need to make a whole new thread.

Question:

Can someone explain to me why the answer is C? It seems odd to me that the maximum height of the projectile goes towards infinity as it approaches a certain Vo. Just trying to think about this intuitively, it seems wrong that an absolute Vo would yield an infinite h.

Maybe I am reading the question incorrectly, and "maximum height" is defined as the highest possible H attainable with this given set up and the Y axis isn't in meters, but actually in %.