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Questions tagged [angular-momentum]

The conserved quantity arising from a rotational invariance. Combine with rotational-dynamics for the classical mechanics approach and quantum-mechanics for the QM interpretation

When to Use this Tag

refers to all situations where a quantity is conserved due to rotational invariance. This may occur both in (esp. ) as well as in . Usually, you should combine with another tag referring to the framework in which you work.

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How does Hubble's constant affect the Earth's orbit

If Hubble's constant is $2.33 \times 10^{-18} \text{ s}^{-1}$ and the earth orbits the sun with average distance of 150 million kilometers; Does that mean the earth's orbital radius increases approximately $11\text{ m}/\text{year}$? Does the…
rae
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Conservation of angular momentum in propeller planes and helicopters

Consider a propeller plane with only one propeller in the front. If the propeller rotates, I would expect by conservation of angular momentum, that the body of the plane would spin in the opposite direction of the propeller but with much lower…
martin
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Having hard time with Angular Momentum and Parallel axis theorem

I'm having hard time with Angular Momentum and Parallel axis theorem. Please explain these 2 formulas. Is one formula derived from the other? $$J = J_{cm} + R_{cm} \times P_{cm}$$ $$I = I_{cm} + MD^2$$ The first formula is for Angular Momentum and…
user1980750
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Conservation of angular momentum when two bodies collide and both spin the same direction

I'm having a hard time trying to understand the conservation of angular momentum. Let's assume the following 2D experiment: At the start of the experiment both rectangles have no angular momentum, but if the upper moves downwards and their corners…
Michael Mahn
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What is the formula for angular momentum in four dimensional formalism of General Relativity?

Might it be $L^{\nu}=(0, \vec L)$, where $\vec L=\int\,\vec p \times \vec r\,dV$ is the three dimensional angular momentum? But latter would hold only for low angular velocities. What is the angular momentum vector in Special Relativity? We must use…
Dmitri Martila
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If the Bohr angular momemtum model has been proven wrong, do electrons in solids really move at all given we find fixed bonding angles?

We have fixed bonding angles for Carbon, Nitrogen, Oxygen and such, so how can the bond stay in place if the electrostatic force underlying from the valence electrons, which are moving all the time. If the electrons move, then then that forces…
user3290084
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Instantaneous value of angular momentum

I am trying to smooth the torque ripples of a shaft by placing on it a unsymmetrical flywheel (having great diameter in positions where torque is low and small one where the torque is great). I have the analytical equation of the torque versus time…
Arnold
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How can you conclude that the angular momentum of a particle moving in a central field of force will be constant?

When determining the magnitude of the angular momentum vector $|\vec L |$, for a particle in a central field, my textbook concludes the following: $L=|\vec{r}\times m\vec{v}| = mr^2\dot{\theta}$ = constant "for any particle moving in a central…
Life_student
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Spinning wheel on rotating stool - why am I also affected even when the wheel axis is horizontal?

So I can point the axis of spin in one horizontal direction - and then move it in another direction (so it stays horizontal - like the picture below). And that still changes the direction of spin (on the rotating stool). Why does that happen? I…
InquilineKea
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Suppose a spinning sphere in a frictionless environment, will it deviate from its location?

I was reading in a patent that a rotating spherical body in space will experience a curvilinear translation, due to the conservation of angular momentum. This confuses me, as per my understanding if there is no friction, or any other force applied,…
Alberdesan
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Conservation of angular momentum even though there is torque

This is a screenshot from my textbook. It says the diver's angular momentum is conserved, and yet it is acted upon by gravity, and that would yield torque on the diver, wouldn't it? But if we were to say the angular momentum of the diver is in…
Lee Laindingold
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Why is the angular momentum conserved in this system?

Considering the formula for angular impulse given by: $$(\mathbf{H}_o)_1+\int_{t_1}^{t_2}\sum{M_o}\,dt=(\mathbf{H}_o)_2$$ Why the sum of torques with respect to 'O' is zero in this system?. Should not the weight of the masses in this system generate…
J. J. Gonzalez
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Can the internal and external angular momentum be added when measured from a different reference system?

The classical definition for angular momentum is L = r x p, which works well for a particle or any object that is internally at rest, or at least not rotating but it fails if the particle is rotating. For example, the Earth’s angular momentum around…
Sergio Prats
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Is angular momentum conserved if you move off at a Tangent?

Lets imagine a binary system of two astronauts in space connected to one another via light rope. The rope is taut and they're spinning round and round with their axis of rotation being the the axis perpendicular to the their centre of mass. Now, my…
Ari Ben Canaan
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Neglecting angular momentum for particles with small size...?

In page 296 and 297 of Kleppner and Kolenkow, The author goes over an example of a massless tilted rod rotating about the z-axis as shown in the figure having two point masses at each end: Details: The perpendicular to rod's length makes an angle…
tryst with freedom
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