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## Homework Statement

A puck, mass m, on the end of a (thin, light) string rotates in a circle of radius r_0

at a speed v_0

on a

frictionless table. The radius of the circle is slowly reduced from its initial value by pulling the string

through a hole in the table.

A. Hence write down an expression for the speed of the mass when the radius is reduced to some radius

r

B. Write down an expression for the tension in the string and show it goes like 1/r^3

## Homework Equations

v=rw

## The Attempt at a Solution

i split the above problem into two systems. rotational and kinematic. the kinetic energy is

0.5mrw^2-0.5^mr_0w^2. For the rotational system i am unsure how this is linked to tension ?. Is my starting point correct ?.