1. A uniform 2.0- cylinder of radius 0.15 is suspended by two strings wrapped around it ( the figure ). As the cylinder descends, the strings unwind from it. 

What is the acceleration of the center of mass of the cylinder? (Neglect the mass of the string.) answer is in m/s^2

2. An ice skater spinning with outstretched arms has an angular speed of 4.0 rad/s .She tucks in her arms, decreasing her moment of inertia by 7.5 percent.

a) Is the resulting angular speed?

b) By what factor does the skater's kinetic energy change?

c) Where does the extra kinetic energy come from (Neglect any frictional effects.)