An ice skater has a moment of inertia of 5.0kgm2 when her armsare outstreched. A

Question

An ice skater has a moment of inertia of 5.0kgm2 when her armsare outstreched. At this time she is spinning at 3.0 recolutionsper second. (rps) If she pulls in her arms and decreases her momentof inertia to 2.0 kgm2, how fast will she be spinning? pleaseanswer with work and i'll love you forever! An ice skater has a moment of inertia of 5.0kgm2 when her armsare outstreched. At this time she is spinning at 3.0 recolutionsper second. (rps) If she pulls in her arms and decreases her momentof inertia to 2.0 kgm2, how fast will she be spinning? pleaseanswer with work and i'll love you forever!

Explanation / Answer

From law of conservation of angular momentum , For an isolated system(where no external torques are acting ) , angular momentum remains conserved . Here in this case also , there is no external force . Skater pulls her arm using her internal energy . Also angular momentum =Moment of ineria * angular velocity. Initially . Moment of ineria = 5.0 kgm2 Angular velocity = 3.0*2 rad/sec Finally Moment of ineria = 2.0 kgm2 Let Angular velocity be rad/sec then equating initial and final angular momentum Iii=Iff     (I stands for moment of inertia ) 30 = 2 So =15 rad/sec Also angular velocity = Number of revolutuion persecond*2 So Number of revolutuion per second=7.5 rev/s

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