A ballet dancer spins about a vertical axis at 120 rpm with arms outstretched. With her arms folded, the moment of inertia about the axis of rotation decreases by 40%. Calculate the new rate of rotation.

A ballet dancer spins about a vertical axis at 120 rpm with arms outst

1.	A ballet dancer spins about a vertical axis at 120 rpm with arms outstretched. With her arms folded, the moment of inertia about the axis of rotation decreases by 40%. Calculate the new rate of rotation.
Answer» Solution :`n_(1)=120 rpm , n_(2)= ?"" I_(1)omega_(1)=I_(2)omega_(2)` Let `I_(1)=100` UNITS, then `I_(2)=60` units `100xx120 = 60xx omega_(2) rArr omega_(2)=200` rpm.