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Homework Help: Centripetal/projectile motion

  1. Mar 26, 2007 #1
    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
     
  2. jcsd
  3. Mar 26, 2007 #2
    none of us can access a file on your computer, you're gonna have to post the question manually.
     
  4. Mar 26, 2007 #3
    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 cuz i need help
     
  5. Mar 27, 2007 #4
    First: This should be posted in Homework Help.

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