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

• Student4Life

## 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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## 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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