Questions and Answers
What happens to the angular velocity of a neutron star during its collapse?
The angular velocity increases.
The units of angular momentum are __________.
kg*m^2/s
Which statement best describes the angular momentum of a merry-go-round when pushed to the left?
Viewed from above, the angular momentum would be negative.
The angular momentum of an object moving in a circle can be calculated using __________.
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What can you say about the angular momentum of the minute hand and the hour hand of an analog clock?
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Is angular momentum conserved for the turntable and putty during the process?
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Both hands of an analog clock have positive angular momentum.
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What happens to the block's speed when you pull the string decreasing its circular path radius?
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In which process is the angular momentum of the object conserved?
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If the wheels from two different kinds of cars have the same mass, same radius, and same angular velocity, they __________.
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What is true about the merry-go-round's angular momentum while the dog is in the air?
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Just before the gear and disk make contact, what can be said about their angular momentum?
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If some quantity, let's call it 'Z,' is conserved for a certain system, during a certain process, that must mean __________.
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What happens to the total angular momentum of the system (turntable, professor, and dumbbells) during the brief process of lowering his arms?
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Without external torques, an object __________.
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Without external torques, an object __________.
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What is true when two kids grab onto each other while sliding on ice?
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After they make contact, what can be said about the gear's angular momentum compared to the disk's?
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After getting a flat tire, how does the lighter wheel's angular momentum compare to the other wheels on the car?
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The magnitude of the angular momentum of a rotating wheel can be directly calculated using __________.
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The angular momentum of a system is conserved during a process only if __________.
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After the dog has landed and the merry-go-round is spinning, what is true about their angular momentum?
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Study Notes
Neutron Stars and Angular Momentum
- During collapse, a neutron star's angular velocity increases due to conservation of angular momentum.
- Angular momentum remains constant in the absence of external torque.
Units of Angular Momentum
- Angular momentum units are kg*m²/s.
- Linear momentum units differ (kgm/s), while kgm/s² denotes force.
Angular Momentum Direction
- When pushing a merry-go-round to the left, its angular momentum appears negative when viewed from above.
Calculating Angular Momentum
- For circular motion, angular momentum formula can be I * ω or m * v * r, where I is rotational inertia, ω is angular velocity, m is mass, v is speed, and r is the radius.
Clock Hands Comparison
- The minute hand of an analog clock has greater angular momentum than the hour hand due to higher angular velocity and greater moment of inertia.
Conservation of Angular Momentum in Systems
- A turntable's angular momentum remains conserved when putty sticks to it as no external torque is applied.
- Angular momentum of a system is conserved if no net external torque acts on it.
External Forces and Systems
- The scenario of two kids grabbing onto each other while sliding on ice maintains a constant total angular momentum.
Interaction of Gear and Disk
- A gear and disk, prior to contact, have the same angular momentum due to their angular speeds and moments of inertia relation.
Effects of Mass on Angular Momentum
- A lightweight wheel on a car will have a smaller angular momentum compared to the heavier, identical wheels when in motion.
Rotational Dynamics
- The angular momentum magnitude for rotating objects is calculated via L = I * ω, as each part of a rigid body has diverse properties.
Non-zero Angular Momentum Scenarios
- After a boy on a merry-go-round catches his dog, both the boy and the merry-go-round possess non-zero angular momentum due to their circular motion.
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Description
Explore the key concepts of angular momentum, its conservation, and practical examples like neutron stars and clock hands. This quiz covers calculations, units, and directionality of angular momentum in various systems.
