Question-

1. In what circumstances can the angular velocity of system of particles change without any change in the system's angular momentum?

1) This cannot happen under any circumstances.

2) This can happen if a net external force acts on the system's center of mass.

3) This can happen if the only forces acting are internal to the system.

4) This can happen if an external net torque is applied properly to the system. 

2. An ice skater has a moment of inertia of 5.0 kgm‚ when her arms are outstretched. At this time she is spinning at 3.0 revolutions per second (rps). If she pulls in her arms and decreases her moment of inertia to 2.0 kgm‚, how fast will she be spinning?

1) 2.0 rps

2) 3.3 rps

3) 7.5 rps

4) 10 rps 

3. A figure skater rotating at 5.00 rad/s with arms extended has a moment of inertia of 2.25 kgm‚. If the arms are pulled in so the moment of inertia decreases to 1.80 kgm‚, what is the final angular speed?

1) 2.25 rad/s

2) 4.60 rad/s

3) 6.25 rad/s

4) 0.81 rad/s