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**1. Homework Statement**

A very slippery ice cube slides in a vertical plane around the inside of a smooth, 20 cm diameter horizontal pipe. The ice cube's speed at the bottom of the circle is 3 m/s.

a) What is the ice cube's speed at the top?

b) Find an algebraic expression for the ice cube's speed when it is at angle theta where the angle is measured counterclockwise from the bottom of the circle. Your expression should give 3 m/s for 0 degrees and your answer to part a for 180 degrees.

**2. Homework Equations**

KE= 1/2mv^2

PE=mgy

**3. The Attempt at a Solution**

Ok, I got part a

(.5)*m*(3m/s)^2=m(9.80)(.2m)+(.5)*m*(vf)^2

vf= 2.25 m/s

But I am really not sure of how to approach part b. I thought about the equations for rotational kinematics, but the acceleration is not constant. Any hints?