Centripetal/Projectile Motion: Proof of Formulas for v^2=mgy

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Homework Help Overview

The discussion revolves around proving the formula v^2 = mgy in the context of centripetal and projectile motion. The original poster is seeking assistance with understanding the derivation of this formula, particularly in relation to a scenario involving a ball on a string that swings and then launches horizontally.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the use of conservation of energy as a potential method for proving the formula. The original poster expresses difficulty in applying formulas correctly and questions the validity of their calculations.

Discussion Status

The conversation is ongoing, with some participants providing guidance on the use of energy conservation principles. There is a lack of consensus on the specific approach to take, and multiple interpretations of the problem are being explored.

Contextual Notes

The original poster has referenced a file that others cannot access, leading to a request for the problem to be stated manually. There is also a mention of specific variables and conditions related to the motion of the ball, which may influence the discussion.

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from the second question in the link, I've been asked to figure out how to proof some of the formulas. Could someone please help me? I tried using some formulas but I keep getting stuck. If it doesn't show, then could someone please help me proof the formula v^2=mgy

file:///C:/Documents%20and%20Settings/Jenny/Desktop/physics%20assignment2.htm
 
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none of us can access a file on your computer, you're going to have to post the question manually.
 
A ball on a string is released from rest with the string horizontal and swings through a quarter circle of radius R. At the bottom of the swing the string breaks and the ball is launched horizontally with speed v. The bottom of the swing is a distance 2R above the floor and the ball lands on the floor a distance d away. I'm using v for velocity, R for radius, and g gravity and a for accelaration
We have to prove that v^2=2gR

I used the formula v^2y-v^2oy=2ay(y-yo)
My final answer was -v^2=4gR...something's wrong here because i need help
 
First: This should be posted in Homework Help.

Second: You can use conservation of energy here to solve it.
 

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