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A skater's changing shape and changing spin

When an ice skater enters a spin with their arms stretched wide and then pulls them tightly into their chest, their rotation suddenly speeds up without anyone pushing them. Pulling mass closer to the axis of rotation reduces the skater's moment of inertia, so conserving angular momentum requires their spinning speed to increase.

3–5 min

Questions you could explore

  • Why can angular momentum remain nearly constant while kinetic energy increases?
  • How would friction or another external torque change the simple skater model?

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Why metal can feel colder than wood

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How can headphones fight noise with more sound?

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3–5 min

How can a ship made of steel float?

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A skater's changing shape and changing spin | Speech Topic | speaking.app