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A 1.1-kg 20-cm-diametersolid sphere is rotating about its diameterat 69 rev/min.

ID: 1671791 • Letter: A

Question

A 1.1-kg 20-cm-diametersolid sphere is rotating about its diameterat 69 rev/min.

a) What is its kineticenergy?
b) If an additional 5.0 mJ of energyare supplied to the rotational energy, what is the new angularspeed of the ball (in rev/min)? a) What is its kineticenergy?
b) If an additional 5.0 mJ of energyare supplied to the rotational energy, what is the new angularspeed of the ball (in rev/min)? A 1.1-kg 20-cm-diametersolid sphere is rotating about its diameterat 69 rev/min.

a) What is its kineticenergy?
b) If an additional 5.0 mJ of energyare supplied to the rotational energy, what is the new angularspeed of the ball (in rev/min)?

Explanation / Answer

moment of inertia. I=2MR^2/5=4,4e-3(kgm2). a) angular speed. 69rev/min=69*2/60(rad/s)=7,23(rad/s). kinetic energy. K=0,115(J). b). K=0,115+5e-3 so '=7,38(rad/s)=70,5(rev/min).