(1) A physics instructor with her arms extended out to her side has a moment of inertia of 5.2 kg m^2 and is rotating at 0.8 rev/s. As she pulls her arms close to her body, her moment of inertia decreases to 2.8 kg m^2. (A) What is her new angular speed? (B) What was the change in her angular momentum? (C) What was the change in her rotational kinetic energy?
(2) A torque of 100 N-m causes a wheel of Moment of inertia, I, equal 100 kg-m^2 to rotate through 4 pi radians. (A) How many turns does the wheels make? (B) What is the angular acceleration of the wheel? (C) What is the final kinetic energy of the wheel. (D) What is the final angular velocity of the wheel?
(3) A Peterbilt truck of mass 10,000 kg is traveling up a 3 degree grade at 30 m/s. There is a wind resistance of 1000 N. The wheels are 0.5 m radius. (A) What is the total force needed to keep the truck moving at constant speed? (B) What is the torque about the driving axle? (C) What is the radial velocity of the wheels? (D) What is the rotation rate of the wheel in RPM