A horizontal disk with moment of inertia I1 rotates with angular ...

[rlane42]

A horizontal disk with moment of inertia I1 rotates with angular speed 1 about a vertical frictionless axle. A second horizontal disk, with moment of inertia I2 drops onto the first, initially not rotating but sharing the same axis as the first disk. Because their surfaces are rough, the two disks eventually reach the same angular speed . The ratio /1 is equal to
  1. I1 / I2
  2. I2 / I1
  3. I1 / (I1 + I2)
  4. I2 / (I1 + I2)

Question 2

Two spheres, one hollow and one solid, are rotating with the same angular speed around an axis through their centers. Both spheres have the same mass and radius. Which sphere, if either, has the higher rotational kinetic energy?
  1.the hollow sphere
  2.the solid sphere
  3.They have the same kinetic energy.1

[TheNamesImani]

Answer to Question 1

3

Answer to Question 2

1