Questions tagged [precession]

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How to calculate the rotation speed of spinning top, which will be enough that it is not falling down or stays within certain angle to vertical axis [duplicate]

I found many articles with the calculation of the precession rotation speed of the spinning top like this or this. They give this equation for Precession rotation speed $\Omega$: $$\Omega=\frac{mgr}{I\...
Zlelik's user avatar
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Physical pendulum: axis of rotation

Why is the angular momentum always considered to be parallel to the angular velocity in physical pendulum problems, as if the axis of rotation were a principal axis always? I don't see the ...
lgotta's user avatar
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When looking at Gyroscopes, does precession only occur if a force is applied perpendicular to the axis of rotation? or can it be a parallel force?

I am trying to simplify gyroscopic precession for PPL Helicopter students and in the process confused myself. Many texts define it as processing a force 90 degrees when the force is applied 'parallel ...
Maryke's user avatar
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1 answer
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GR correction to perihelion precession comparing with newtonian orbit

My professor did the following derivation of the formula for the perihelion precession $\delta \phi = \frac{6\pi G M}{a(1-e^2)}$, but I am missing a factor of 2. I would appreciate if someone can help ...
Damiano Scevola's user avatar
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Thomas precession and the whether or not the two frame can be directly boosted in special relativity

In the common treatment of the Thomas precession, there are three frames: the rest frame of the nucleus the instantaneous frame associated with the electron at the time t, having a velocity of v in ...
Dzhou's user avatar
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1 answer
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Free Body Diagram of Precessing Top

Consider a heavy, symmetric top spinning on a table, initially inclined at some angle from the vertical. Assuming this angle is fixed, it follows that the weight $\textbf W$ and normal force $\textbf ...
William Deng's user avatar
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1 answer
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Which direction will the gymnastics tilt twist turn me? Figuring out rotation direction in torque-free precession

I'm trying to understand the physics of tilt twisting in gymnastics / trampolining, and I've run into a conundrum where theory doesn't seem to agree with practice, so I'm looking for where my mistake ...
Gabi's user avatar
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Does the accelerated expansion of the universe have any effects in the orbital precession of galaxies? And in their eccentricity?

I found several papers (https://iopscience.iop.org/article/10.3847/2041-8213/ace90b; https://link.springer.com/article/10.1134/S1063772920100054; https://arxiv.org/abs/gr-qc/0301057; https://arxiv.org/...
vengaq's user avatar
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Two speeds of precession without nutation

I understand mathematically that when you look for solutions to the equations of motion of a spinning symmetric top with a constant inclination angle $\theta$, you get a quadratic equation with two ...
PatrickComposerPhysicist's user avatar
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Direct calculation of the geodetic precession for the comoving observer

In the text book "Gravity" written by Hartle (p.302), the precession angle per orbit of a gyroscope, initially lied in the equatorial plane and in the radial directon) moving in a circular ...
kderakhshani's user avatar
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Choice of axis in analysis of gyroscopic precession

In many demonstrations of analysis of gyroscopic precession, the analysis goes on by choosing two axes, one about which angular momentum is calculated, another about which torque of gravity is ...
Eisenstein's user avatar
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Why does the period of precession of a gyroscope have to be way larger than it's spin period so that it's motion can be modelled?

Mathematically, torque induced gyroscopic precession may be modelled with the following equation: $$ {\displaystyle T_{\mathrm {p} }={\frac {4\pi ^{2}I_{\mathrm {s} }}{\ mgrT_{\mathrm {s} }}}={\frac {...
ThincThru's user avatar
1 vote
1 answer
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Energy conservation in Landau-Lifshitz Equation [closed]

considering the Landau-Lifshitz equation for magnetisation dynamics, $\frac{\vec{M}}{dt}=-\gamma (\vec{M} \times \vec{H})$ In this article (https://arxiv.org/abs/1101.1005), the author argues that $\...
femtokitty's user avatar
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2 answers
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What effects do we have to take in account to calculate the total precession of a gyroscope orbiting close to a black hole?

I've read about the Lense–Thirring precession which applies to bodies orbiting rotating masses. But there is also the geodetic effect (de Sitter precession), which is caused by the curvature of ...
Stellar_Enginner's user avatar
4 votes
1 answer
238 views

Spinning Wheel subjected to Gravitational Force

have a question about the dynamics of a suspended horizontally rotating wheel subjected to gravitational force like in following picture I took from here: At the beginning the wheel has an angular ...
user267839's user avatar
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3 votes
1 answer
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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 ...
Richard's user avatar
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4 answers
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Why do bullets precess in the opposite direction from gyroscope diagrams?

Bullet spin causes a bullet to become a gyroscope. Specifically, bullets have their center of pressure in front of their center of mass. Therefore, when pressed, gyroscopic forces cause a bullet to ...
Johnlpmark's user avatar
1 vote
1 answer
130 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 ...
Ebi's user avatar
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7 votes
3 answers
517 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 ...
Ankit's user avatar
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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 ...
Python House's user avatar
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0 answers
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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 ...
ShoutOutAndCalculate's user avatar
1 vote
1 answer
158 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 ...
heranias's user avatar
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1 answer
196 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 ...
Relativisticcucumber's user avatar
2 votes
2 answers
149 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 ...
Eli Yablon's user avatar
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1 answer
586 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 ...
bnosnehpets's user avatar
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1 answer
52 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. ...
Daniel's user avatar
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1 answer
483 views

Why is precession angular velocity of a gyroscope independent of the angle of its axis?

I'm making gyroscopes in my shop and studying precession. Studied dynamics in 1964 so may have forgotten a thing or two. Consider a gyroscope or top spinning with its axis at angle $\beta$ with ...
Bill's user avatar
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1 answer
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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: ...
user1611107's user avatar
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1 answer
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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. ...
slithy_tove's user avatar
1 vote
1 answer
78 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 ...
111's user avatar
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1 answer
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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/...
Krešimir Bradvica's user avatar
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1 answer
154 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 ...
rcgldr's user avatar
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0 votes
1 answer
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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 ...
Salvatore Manfredi D's user avatar
1 vote
1 answer
100 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: ...
Sato Yusei's user avatar
1 vote
3 answers
339 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 ...
Matteo Menghini's user avatar
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0 answers
27 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 ...
Museful's user avatar
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0 votes
1 answer
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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 ...
archil kitiashvili's user avatar
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1 answer
63 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 ...
Space Thoughts's user avatar
1 vote
2 answers
232 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 ...
Harris Ryder's user avatar
0 votes
1 answer
80 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 ...
Edward Roscoe's user avatar
0 votes
2 answers
345 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 ...
Red Act's user avatar
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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 ...
Alexander Spacelifter's user avatar
2 votes
1 answer
66 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 ...
Markoul11's user avatar
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-2 votes
2 answers
548 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 ...
Alexander Spacelifter's user avatar
3 votes
1 answer
208 views

Kinematics of a rolling disk on a static disk (variation of the Euler disk)

I'm puzzled by the following problem. Consider a simple tilted disk $\mathcal{D}$ of radius 1 (in any unit) rolling without sliding on top of a static horizontal disk $\mathcal{S}$. The normal $\...
Cham's user avatar
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1 vote
1 answer
143 views

Is Bertrand's Theorem Consistent with GR?

Bertrand's Theorem - Please observe the gif of orbits with different exponents in the denominator. (I couldn't get the image upload feature to work for this) Note, the orbit with a 1.9 exponent ...
HardlyCurious's user avatar
2 votes
1 answer
127 views

What explains the descrepancy between Asaph Hall's equation for Mercury's precession and GR?

In regard to What is the weight equation through general relativity?, the answer is: $$F=ma=\frac{GMm}{r^2}\frac{1}{\sqrt{1-\frac{2GM}{c^2r}}}.$$ This source provides a different equation: $$f \approx ...
HardlyCurious's user avatar
6 votes
1 answer
679 views

Does motorcycle counter-steering work by precessional motion?

When a motorcycle is going over a particular speed ($\approx 20$ m/h or 30 km/h) you learn in motorcycle class the best way to steer is using the so-called "counter steering"; I can't find ...
nammerkage's user avatar
4 votes
1 answer
2k views

Newtonian contribution to perihelion precession of Mercury

We have seen that the orbits of the planets around the sun can be found, to a good approximation, by only considering a two-body system (a planet and the sun) interacting through a central force. ...
PG1995's user avatar
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0 votes
1 answer
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Gyroscopes and Conservation of Angular Momentum follow-up

I'd like to follow up on a question I asked two years ago under the same title (Sept. 22, 2019). I am trying to understand just exactly how angular momentum around the vertical axis is conserved ...
puzzled's user avatar
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