Joey, whose mass is m = 36 kg, stands at rest at the outer edge of a frictionless merry-go-round with the mass M = 300 kg and the radius R = 2.0 m. The merry-go-round is also at rest. Joey then begins to run around the perimeter of the merry-go-round, finally reaching a constant speed, measured relative to the ground, of 4.0 m/s. What is the final angular speed of the merry-go-round?

Explanation:

Given:

mass of person,

mass of merry go-round,

radius of merry go-round,

velocity of the person running,

We consider merry go-round as a ring:

Now the moment of inertial of the ring is given as,

Moment of inertia of the person considering as a point mass:

Now according to the conservation of angular momentum:

where:

angular velocity of the merry-go-round

angular velocity of the person running

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the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.