Momentums equation is just p=mv
mass times velocity so 50x200
p=10,000
Explanation:
The tangential speed of Andrea is given by :

Where
r is radius of the circular path
ω is angular speed
The merry-go-round is rotating at a constant angular speed. Let the new distance from the center of the circular platform is r'
r' = 2r
New angular speed,

New angular speed is twice that of the Chuck's speed.
It looks that way cause the earth is rotation on its axis
Mechanical advantage allows you to apply a force over a short distance to increase the distance and object moves.