A small block on a frictionless, horizontal surface has a mass of 0.0250 kg. It is attached to a mass less cord passing through a bole in the surface (Fig. 10.48). The block is originally revolving at a distance of 0.300 m from the bole with an angular speed of 1.75 rad/s. The cord is then pulled from below, shortening the radius of the circle in which the block revolves to 0.150 m. Model the block as a particle.
(a) Is angular momentum of the block conserved? Why or why not?
(b) What is the new angular speed?
(c) Find the change in kinetic energy of the block.
(d) How much work was done in pulling the cord?