A figure skater spins with arms extended. When she pulls her arms in, what happens to her angular velocity?
Practice Questions
1 question
Q1
A figure skater spins with arms extended. When she pulls her arms in, what happens to her angular velocity?
Increases
Decreases
Remains the same
Becomes zero
By conservation of angular momentum, pulling arms in decreases moment of inertia, thus increasing angular velocity.
Questions & Step-by-step Solutions
1 item
Q
Q: A figure skater spins with arms extended. When she pulls her arms in, what happens to her angular velocity?
Solution: By conservation of angular momentum, pulling arms in decreases moment of inertia, thus increasing angular velocity.
Steps: 6
Step 1: Understand that the figure skater is spinning. This means she has angular momentum, which is a measure of how much motion she has while spinning.
Step 2: Know that angular momentum is conserved. This means that unless an external force acts on the skater, her total angular momentum will stay the same.
Step 3: Recognize that the skater has a moment of inertia, which is a measure of how spread out her mass is from the center of her spin. When her arms are extended, her moment of inertia is larger.
Step 4: When the skater pulls her arms in, her moment of inertia decreases because her mass is now closer to the center of her spin.
Step 5: Since angular momentum is conserved, if the moment of inertia decreases, the angular velocity (how fast she spins) must increase to keep the angular momentum the same.
Step 6: Conclude that when the skater pulls her arms in, her angular velocity increases.
