How Does Friction Torque Affect Angular Speed in a Spinning Spherical System?

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thecombover
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A uniform spherical shell of mass 9.00 with diameter 54.0 has four small masses of mass 2.00 attached to its outer surface and equally spaced around it. This combination is spinning about an axis running through the center of the sphere and two of the small masses
Diagram of a uniform sphere spinning about a vertical dashed spin axis through its center, with four small brown masses on its surface: two on the axis at top and bottom, and two on the equator at left and right.


What friction torque is needed to reduce its angular speed from 80.0 to 55.0 in a time interval of 35.0 ?
 
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Welcome to PF!

thecombover said:
… What friction torque is needed to reduce its angular speed from 80.0 to 55.0 in a time interval of 35.0 ?

Hi thecombover! Welcome to PF! :smile:

Circular version of good ol' Newton's second law …

net torque = rate of change of angular momentum …

so how much angular momentum do you need to change? :wink:
 

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