Mistake Master
Mistake Master · AP Physics 1 · Unit 6 · Step-Through Animation
The Third Ledger: Angular Momentum
You'll learnthat angular momentum is conserved with no external torque, while rotational energy need not be.
A skater pulls her arms in and spins faster — no push, no engine, no trick. A blob crashes a spinning disk and everything slows. Two very different shows, one frozen number, and a second ledger that refuses to sit still.
ROTATION LAB
Before you start
What you're looking at
A skater spinning with arms stretched wide, and two separate ledgers reading her spin on the right.
The question
How can a skater spin faster when nothing outside her pushes on her?
Watch for
Which of the two ledgers refuses to move as she changes her shape.
What the symbols mean
The pink bar is angular momentum L; the other ledger is rotational kinetic energy; readouts give I and ω.
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