A merry-go-round has a radius of 2.0 m and a moment of inertia 300 kg⋅m2. A boy of mass 50 kg runs tangent to the rim at a speed of 4.0 m/s and jumps on. If the merry-go-round is initially at rest, what is the angular velocity after the boy jumps on?
A star collapses which greatly increases its density. The -kg-mass of the star remains the same throughout the collapse, as does the star’s mass distribution, which is uniformly spherical. Before collapse, the star’s radius was km and it had a rotational period of 28 days. The star’s radius is km after the collapse, what is its rotational period? Consider a day to be equal to seconds.