Question

A figure skater is spinning on frictionless ice. Treat the figure skater as a sphere with radius R=.4m and mass M=60kg. The skater is holding onto a massless string attached to a weighted ball of m=10kg. The skater is initially spinning at an angular speed w0 of 2pi radians per second (1 rev/s) with a sting radius of r=1m. Moment of inertia for a sphere is I=(2/5)MR^2. 1.) What is the initial total rotational inertia of the skater and ball? 2.) What is the angular momentum of the skater and ball? 3.) While spinning, the skater shortens the sting to a new radius of r=.2m. What is the new rotational inertia of the skater and ball? 4.) What is the new angular speed wf of the skater and ball in rev/s? 5. How much did the rotaional kinetic energy of the skater and ball increase? Where did this energy come from?

Answer 1

Thanks for asking.