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A 1.6 kg disk with radius 0.63 m is rotating freelyat 55 rad/s around an axis pe

ID: 1680827 • Letter: A

Question

A 1.6 kg disk with radius 0.63 m is rotating freelyat 55 rad/s around an axis perpendicular to its center. Asecond disk that is not rotating is dropped onto the first disk sothat their centers align, and they stick together. The mass of thesecond disk is 0.45 kg and its radius is 0.38 m. What isthe angular velocity of the two disks combined? A 1.6 kg disk with radius 0.63 m is rotating freelyat 55 rad/s around an axis perpendicular to its center. Asecond disk that is not rotating is dropped onto the first disk sothat their centers align, and they stick together. The mass of thesecond disk is 0.45 kg and its radius is 0.38 m. What isthe angular velocity of the two disks combined?

Explanation / Answer

By conservation of angular momentum:

I =I’’…………..(I=moment ofinertia=mr2 for solid disc and = angularvelocity)

I1=(I1+I2)’

=>1.6x0.632x55=(1.63x0.632 +0.45x0.382) ’

=>’=49.06 rad/s