- #1

mazz1801

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**A ball is attached to an inextensible string of negligable mass and hangs vertically under gravity. At time t=0, it is given a horizontal velocity u and begins to move in a vertical circle of radius r. At any time t>0, the ball is at an angle θ to the vertical and has a velocity v tangential to its circle of motion. There is no friction acting so that the mechanical energy of the ball is conserved/**

**If**

^{u}=4rg, find the angle θ at which the string goes slack. For how long will the string remain slack before becoming taut again?I'm having trouble even starting with this part of the question.

*(The first part was to prove that the difference in tension at the bottom and tension at the top was 6 times the weight of the ball- I got that bit)*

I have tried using the equations for motion in a circle. Basically all of them and they are all leading me down the same street!

I'm pretty desperate here... could someone just tell me what equation I should be using!

Also will the answer be numerical or contain m and g...