A 50 kg skater moving at 5 m/s over frictionless ice grabs a rope stretched out 10m from a post and perpendicular to her path. She then moves in circles, spiraling inward as the rope wraps around the post. How fast is she moving when she is 2 meters from the post?

Answer 1

angular momentum must conserved.
OrigAngMomentum=finalangmomentum
I*wi=Iwf
M*ri^2*vi/ri=M*rf^2*Vf/rf

Vi*ri=Vf*rF

vf=5*10/2 m/s