A merry-go-round is a common piece of playground equipment. A 3.0-m-diameter merry-go-round, which can be modeled as a disk with a mass of 300 kg , is spinning at 23 rpm. John runs tangent to the merry-go-round at 4.4 m/s, in the same direction that it is turning, and jumps onto the outer edge. John's mass is 30 kg. Required:
What is the merry-go-round's angular velocity, in rpm, after John jumps on?

The merry-go-round's angular velocity 23.84 RPM

Explanation:

Given;

diameter of merry go round, d = 3 m

radius of the merry go round, R = 1.5 m

mass of the merry go round, m = 300 kg

angular velocity = 23 rpm

velocity of John, v = 4.4 m/s

mass of John, m = 30 kg

Apply conservation of angular momentum;

where;

I is moment of inertia of disk

Substitute in this value in the above equation;

1 rad/s = 9.5493 rpm

2.496 rad/s = 23.84 RPM

Therefore, the merry-go-round's angular velocity 23.84 RPM

jupiter is the largest planet in our solar system, having a mass and radius that are respectively, 318 and 11.2 times that of earth. suppose that an object falls from rest near the surface of each planet and that the acceleration due to gravity remains constant during the fall. each object falls the same distance before striking the ground. determine the ratio of the time of fall on jupiter to that on earth.