Two identical twins hold on to a rope, one at each end, on asmooth, frictionless ice surface. They skate in a circle about thecenter of the rope (the center of mass of the two-body system) andperpendicular to the ice. The mass of each twin is 78.0 kg. Therope of negligible mass is 4.0 m long and they move at a speed of4.90 m/s.
(a) What is the magnitude, in kg · m2/s, of theangular momentum of the system comprised of the two twins?
(b) They now pull on the rope and move closer to each other sothat the rope between them is now half as long. Determine thespeed, in m/s, with which they move now.
(c) The two twins have to do work in order to move closer toeach other. How much work, in joules, did they do? This is the sameas the change in kinetic energy.
