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# Questions tagged [precession]

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### Is the Laplace-Runge-Lenz vector applicable for test particle motion around black holes?

In classical mechanics , the Laplace-Runge-Lenz (LRL) vector is a characteristic feature of the Kepler problem. This enables a very simple discussion of the properties of the orbit for the problem. It ...
82 views

### Why does the gyroscopic precession of a spin-stabilized bullet cause drift in the same direction as the spin?

I am trying to understand the physics behind the gyroscopic phenomenon called spin drift. Spin drift occurs to bullets that are spin-stabilized over the course of their flight. Spin drift starts with ...
1 vote
70 views

### Is Energy conserved in a spinning top?

When we spin a top (give it kinetic energy $K_0$) and place it on a table, it starts precessing around the vertical axis. Is the total energy of the spinning and precessing top equal to the initial ...
250 views

### Weird rotational motion of a heavy thick disc

I and my friend noticed a strange behaviour of a rotating disc (or a cylinder) and we don't know how is that happening. This is the video. Actually what is happening in the video is that the disc ...
1 vote
33 views

### How to calculate the distance of Mercury's perihelion shift in meters? [closed]

Since the shift in mercury's perihelion shift is 2.88E-5 degrees and mercury's altitude above the Sun at its perihelion is 46001200000 meters, can I use the formula for an isosceles triangle to ...
69 views

### How to obtain Mercury Precession equation $\frac{d^2u}{d\theta^2}+u=a$?

Let $r=R(t)$ and $\theta=\Theta(t)$ describe the orbit of the planet. Define $$u(\theta)\equiv\frac{\bar r}{R[\Theta^{-1}(\theta)]}$$ where $\bar r=5.83\times 10^{12}$ cm be the mean value of the ...
52 views

### Response of a loop of current vs. a rigidly rotating charged ring to a magnetic field

In a uniform magnetic field, a loop of current on a wire will feel a torque that makes the magnetic moment of the loop align with the field direction. But for a rigidly rotating ring of charge, its ...
52 views

### How can I conceptually interpret spin precession?

In Sakurai section 2.1, he works through an example of spin precession where we come to the conclusion that, when working in the z-basis and applying a magnetic field in the z-direction, the spin ...
119 views

### Pencil doesn't act as a spinning top

If one spins a spinning top, it'll stay up for a while before falling down. However, if one spins a pencil, it falls down immediately, just like if you didn't spin it at all. My question is why there ...
200 views

### Gyroscopic bicycle wheel - forces on the wheel only

This is a standard problem in university physics, which I studied at university in depth. With higher concepts like angular momentum, it is fairly straightforward to explain the motion. However, one ...
49 views

### Can orbiting point masses precess?

In a recent Science News, it mentioned two orbiting black holes (which later combined) were precessing; i.e. their motion did not remain in a stable plane, but rather the plane itself was changing. ...
23 views

### Is the diameter of earth's north pole similar to the south? (Think axis of rotation+ axis of precession)

Earth is an oblate spheroid, not a sphere, since it's rotation around the axis causes it to bulge along the equator. Is it teally a symetric oblate spheroid though, or also not even that? To explain: ...
31 views

### NMR without static magnetic field

NMR is usually conducted by first aligning nuclei to a strong, constant magnetic field, so that you can apply RF radiation with a magnetic component directly perpendicular to the constant field. ...
1 vote
53 views

### Geodetic Precession of a Gyroscope in Hartle's GR Book

In 14.3, Hartle deduces the geodetic precession angle per orbit of a gyroscope in Schwarzschild geometry. Immediately after eq.(14.18), the book reasons that the angle deduced is physically measured ...
132 views

### Is it right assume the greater the precession of a type of particle in the same magnetic field the slower the particle spin?

Is it right that the greater the Larmor frequency of a particle measured for same magnetic field applied the slower a particle spin is? I read these articles http://hyperphysics.phy-astr.gsu.edu/hbase/...
93 views

### How can precession produce a torque in the direction of precession when it has no angular momentum?

I this video, an 8 lb gyro on a rod supported at one end is spun up to several thousand rpm, and an assist is use to get the axis nearly horizontal. A small stick is used to nearly instantly stop the ...
160 views

### Proton spin precession and alignment to magnetic field in NMR

Precession due to magnetic field occurs when the magnetic moment of a small coil is proportional to its angular momentum ($\vec{m}=g\vec{L}$). This is due to Euler momentum equation, which for such a ...
75 views

### Direction of angular velocity vector VS angular momentum vector

I understand that angular velocity and angular momentum velocities don’t need to be parallel to each other. However, I’m confused what these vectors even represent. So I have 3 questions about this: ...
1 vote
228 views

### Confusion about the Spinning Top

Consider the following symmetric spinning top with a fixed point on the horizontal surface. I have two questions concerning its motion: let $\underline{\Omega}$ denote the precession angular ...
25 views

### Is it possible to change the speed at which a wheel is freely spinning by moving only its axle?

Suppose we have a wheel spinning on a perfectly lubricated axle. Is it possible to change its angular velocity about that axle, by moving only the axle? Due to the wheel's symmetry about the axle's ...
40 views

### Non-swinging Foucault's pendulum

If there is a stationary pendulum, say at the North pole, neglecting torsion, etc. will it seem like spinning around its axis from the reference frame fixed to the Earth's surface. If so, will it ...
48 views

### Will the inner gimbal continue to rotate if no friction?

The picture shows a gyroscope with a rotating disk. Adding a force to the outer gimbal from a certain direction causes the inner gimbal (plus the disk with bearings) to rotate as well. When the force ...
112 views

### Resisting Precession of a Gyroscope

its known that if a torque is applied to a spinning gyro, the gyro will pitch. There's a lot physics on the pitch speed, but what is the torque to induce this pitching? ps. I am building a gyro ...
65 views

### Equation to tell if precession will happen?

So I have an seen the equation to calculate precession but it breaks down at when there is not sufficient angular momentum, for example if an object is not spinning we divide by zero and the ...
217 views

### "Precession" of a free electron

I'd like to gain as deep of an understanding as possible of the following diagram from Introductory Quantum Mechanics, 4th ed., by Richard Liboff: I'm not looking for help with solving the easy ...
67 views

### Definition of rotation moment in a vertical surface during forced precession of a gyroscope

I have the following assumption: Moment of gyroscope flywheel created by gravity force: Rotation moment of natural precession due to gravity forces: Since the flywheel does not drop: However, when ...
58 views

### Puzzle with the precession of the neutron spin?

More perplexing news about the neutron spin in this recent Nature Physics publication: arxiv.org/abs/2103.03333 The authors collaboration (more than 100 authors) report a newly experimentally found ...
370 views

### Antigravity force in powered precession gyroscope [closed]

I have an idea that a powered for rotation gyroscope with fixed precession can serve as antigravity engine. I also wonder of someone tried an experiment to prove that it does not work. The following ...
140 views

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### How do I calculate Earth's axial precession in an idealized Sun-Earth system?

I am experimenting with an idealized two-body system based on the Sun-Earth system. I want to calculate how much Earth's axis precesses and nutates given the simplified setup. In my system, the orbit ...