A playground merry-go-round has a disk-shaped platform that rotates with negligible friction about a vertical axis. The disk has a mass of 200kg and a radius of 1.8 m. A 36-kg child rides at the center of the merry-g-round while a playmate sets it turning at 0.25 rev/sec. If the child then walks along a radius to the outer edge of the disk, how fast will the disk be turning.(adsbygoogle = window.adsbygoogle || []).push({});

Work:

[tex]\omega_0 = 0.5\pi [/tex] rad/sec.

[tex] I_0 = \frac{1}{2} m r^2 [/tex] (MOI for disk).

[tex] L = I_0\omega_0 = \frac{1}{2} m r^2 \omega_0 [/tex]

So, if angular momentum is conserved, [tex] L = I_f\omega_f [/tex]

My only problem is figuring out the MOI for a disk with an object spinning around the outer edge. Anyone know?

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# Conservation of momentum on merry-go-round

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