- #1

grassstrip1

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1. Homework Statement

1. Homework Statement

When the 3.2-kg bob is given a horizontal speed of 1.5 m/s, it begins to rotate around the horizontal circular path A. The force F on the cord is increased, the bob rises and then rotates around the horizontal circular path B. (picture included)

## Homework Equations

L = I ω v = rω

## The Attempt at a Solution

The solution from the book goes into a long procedure with summation of forces to find the angle etc. I tried this

Since there is no moment about the z axis angular momentum is conserved about the z axis. I

_{1}ω

_{1}= I

_{2}ω

_{2}

For a particle I= mr

^{2}so initially, I = (3.2)(0.6sinθ)

^{2}and after I = (3.2)(0.3sinθ)

^{2}. For ω, initially it is (0.6)(sinθ)(1.5m/s) at the end is is (0.3sinθ)(v

_{2})

Setting these equal to each other and solving gives v=12m/s But the answer is 2m/s Not sure where im going wrong. Thank you!