Calculating speed in circular motion

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Anon2459
1. Homework Statement

A whirlygig is made by hanging a mass, m1 = 386.0 g, through a tube and then spinning another mass, m2 = 198.0 g around so that it forms a circle. When this happens the string makes a small angle with the horizontal as shown in the diagram. If this is done at a specific speed then m1 does not move up or down, for this question assume than m2 is moving at this speed. Also assume that there is no friction between the string and the tube.

Tension force acting on m2 is 3.7828

The length of the string between the tube and m2, l, is measured and found to be 81.3 cm. What is the speed of m2?

Homework Equations



F = m x r^2/r

The Attempt at a Solution


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3.7828 = 198.0 x V^2/81.3

Where did i go wrong?
 
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Two things: (1) The tension force is not the centripetal force (2) The length of the string is not the radius of the circle that m2 travels.

Key: What angle does the string make?