If a figure skater is spinning around with her arms outstretched, why will she s

Question

If a figure skater is spinning around with her arms outstretched, why will she spin faster if she brings her arms in?

Momentum is always conserved. By bringing her arms in she is decreasing her mass. With less mass, in order to keep her momentum constant she must spin faster. By bringing in her arms she is reducing the air drag on her and hence, she spins faster.      Angular momentum is always conserved. By bringing her arms in she is decreasing her radius. In order to keep her angular momentum from changing, she must spin faster. Energy is always conserved. By bringing her arms in she is decreasing her PE. To keep her total energy constant her KE must increase. Hence, she spins faster.

Explanation / Answer

Angular Momentum must be conserved: by bringing her arms in she is changing the radius as a consequence of which her moment of inertia is reduced which increases her angular frequency, thus she spins at a faster rate as compared to when her hands were strechted out.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.