Which statement says what an object's momentum is?
A figure skater plants her toe and spins in place. Nothing about her position changes: she stays on one spot. Yet something about her motion is plainly there, something a standing skater does not have. She carries rotation.
You know that a moving object carries momentum. Rotation has its own version of the same idea.
Angular momentum is the rotational analogue of momentum: momentum is the quantity a moving object carries, and angular momentum is the quantity a spinning or orbiting object carries.
The spinning skater carries angular momentum about her spin axis.
Spinning is not the only way. An orbiting object also carries angular momentum: a planet circling the Sun carries angular momentum about the Sun.
A turning Ferris wheel carries it. A spinning top carries it.
A book resting on a shelf carries none: it neither spins nor orbits. And a sled sliding straight without spinning carries momentum, but no angular momentum. Spin-or-orbit is the one thing the sled is missing.
For now the idea stays qualitative: which objects carry angular momentum, and about what. How the spin rate can change while the carried amount does not is the next lesson's story.
What does an object's angular momentum measure?
A basketball spins on a fingertip. Does the ball carry angular momentum?
The ball spins about the axis through the fingertip.
A spinning or orbiting object carries an amount of rotation, called its angular momentum.
Yes. The spinning ball carries angular momentum about its spin axis.
Which of these objects carries angular momentum?
A hockey puck glides in a straight line across the ice without spinning. Does the puck carry angular momentum?
The puck moves, so it carries momentum.
But it neither spins nor orbits, so it carries no amount of rotation.
No. The gliding puck carries momentum, but no angular momentum.
Nestor says: 'A satellite circling Saturn carries angular momentum about Saturn.' Is he correct?
Which statement about angular momentum is correct?
Which of the following carries angular momentum?
A gymnast somersaults in the air, rotating about an axis through her middle. What is the name for the amount of rotation she carries?