A figure skater spins with arms extended. When she pulls her arms in, what happe
Practice Questions
Q1
A figure skater spins with arms extended. When she pulls her arms in, what happens to her rotational speed?
Increases
Decreases
Remains the same
Becomes zero
Questions & Step-by-Step Solutions
A figure skater spins with arms extended. When she pulls her arms in, what happens to her rotational speed?
Step 1: Understand that the figure skater is spinning with her arms out. This is her starting position.
Step 2: Know that when she pulls her arms in, she changes her body shape while spinning.
Step 3: Recognize that pulling her arms in makes her moment of inertia smaller. Moment of inertia is a measure of how spread out her mass is.
Step 4: Remember the principle of angular momentum, which states that if no external forces act on a spinning object, its angular momentum stays the same.
Step 5: Since her moment of inertia decreases when she pulls her arms in, her rotational speed must increase to keep the angular momentum constant.
Angular Momentum Conservation – The principle that the total angular momentum of a closed system remains constant if no external torques act on it.
Moment of Inertia – A measure of an object's resistance to changes in its rotation, which depends on the mass distribution relative to the axis of rotation.
Rotational Speed – The rate at which an object rotates, often measured in revolutions per minute or radians per second.