A ball of mass M attached to a string of length L moves in a circle in vertical plane. At the top of the circular path, the tension in the string is twice the weight of the ball. At the bottom, the ball just clears the ground. Air resistance is negligible. Express all answers in terms of M, L, and g.(adsbygoogle = window.adsbygoogle || []).push({});

A) Determine the magnitude and direction of the net force on the ball when it is at the top.

I know that ƩF=T=Fc but that's about all I can get. Can someone please help.

B) Determine the speed v initial of the ball at the top.

I did;

ƩF=T+mg= mv^2/L and since T=2mg+mg=3mg

so

3mg=mv^2/L

the masses cancel out and you take the square root of whats left so

v=the square root of 3lg

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# Homework Help: Circular motion and orbits AP Physics

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