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Circular Motion: Swinging a rock on a string in a vertical circle...

  • #1

Homework Statement

:[/B]
One swings a rock at the end of a string. We wish for the string to remain taut and for the rock to travel in a circulat path, in a vertical plane. What mathematical condition must the centripetal acceleration of the rock satisfy for the string to remain taut when the rock is at its highest point?


Homework Equations

:[/B]
[F[/c] = m[v][/2] / r ????



The Attempt at a Solution


So far I come up with this equation to define what is going on but I am not sure [F[/c] = m[v][/2] / r ????
 
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Answers and Replies

  • #2
kuruman
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Homework Statement

:[/B]
One swings a rock at the end of a string. We wish for the string to remain taut and for the rock to travel in a circulat path, in a vertical plane. What mathematical condition must the centripetal acceleration of the rock satisfy for the string to remain taut when the rock is at its highest point?


Homework Equations

:[/B]
[F[/c] = m[v][/2] / r ????



The Attempt at a Solution


So far I come up with this equation to define what is going on but I am not sure [F[/c] = m[v][/2] / r ????
You need to do better than that. Draw a free body diagram for the rock when it is at the top of the trajectory, interpret it in terms of Newton's 2nd law, then write down the equation.
 
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