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Feynman Lectures: 20–3 The gyroscope

In the The Feynman Lectures on Physics, Volume I, Chapter 20, Section 3,The Gyroscope found here, Feynman wrote We note that when the wheel is precessing, the particles that are going around the ...
2 votes
1 answer
1k views

Precession of Mercury (Python simulation)

I was trying to simulate the precession of Mercury based on the perturbed solution, and my questions about its implementation in python can be seen here: https://scicomp.stackexchange.com/questions/...
0 votes
1 answer
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Is this an example of precession, or is its motion more complicated?

Let's say there is a solid cylinder floating in space and rotating about its axis of symmetry at rate $\omega$. At time t = 0 a force constant in magnitude is applied to the bottom of the cylinder. ...
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Experimental liimits on torque free precession of spin?

Inspired by this question, I'd like to know what experimental limits there are on the torque-free precession of particle spin. This is a classical phenomenon, not part of quantum theory, but only ...
5 votes
1 answer
4k views

How to show circular orbit as a precessing ellipse

A uniform distribution of dust in the solar system adds to the gravitational attraction of the sun on the planet an additional force linear in $r$ where m is the mass of the planet, k is a constant (...
-1 votes
1 answer
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I have a question about the gravity probe B geodectic precession formula and why it seems to be twice the planetary precession formula

Specifically, I can work out the planetary precession formula to give radians per orbit as $$6 \times \pi \times GM/c^2r$$ (and I find that on the web at places like http://farside.ph.utexas.edu/...
4 votes
1 answer
255 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 ...
3 votes
1 answer
217 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 $\...
1 vote
0 answers
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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\...
2 votes
2 answers
57 views

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 ...
1 vote
1 answer
841 views

Nutation frequency for a weighted gyroscope

So, I've been led to believe that the frequency of nutation of a gyroscope can be calculated using the formula In which the I's are the moments of inertia around the principal axes and omega-3 is the ...
0 votes
1 answer
526 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 ...
1 vote
1 answer
245 views

Minimum gyro speed to yield force precession

Does anyone know what the minimum speed of a gyro to make it so a force at 0deg will yield a movement at 90deg? or even better, what the angle is wrt speed? see http://www.copters.com/aero/gyro.html ...
1 vote
2 answers
481 views

How much force is required to break precession?

Gravity, in this diagram, provides a downward force creating a torque that causes the wheel to precess around the chain. This is cool but counter intuitive, and I am wondering what force is needed to ...
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1 answer
325 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 ...
1 vote
2 answers
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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 ...
0 votes
1 answer
463 views

Larmor Frequency for Spin Transition

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/larmor.html Consider the process of Larmor precession of the magnetic moment associated with the spin angular momentum of an electron inside a ...
1 vote
1 answer
661 views

NMR: Why does 180 degree pulse turn around direction of lamor precession?

In descriptions of the spin echo measurement sequence, it says first a $90°$ pulse turns the magnetization sum vector into the transversal plane where it rotates with the Larmor frequency spins of ...
1 vote
1 answer
62 views

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 ...
5 votes
4 answers
5k views

Precession and alignment in a magnetic field

I am very confused about the concept of alignment in a magnetic field. Perhaps I am also confusing two different phenomena and that may be the issue. My classical understanding of a dipole says that ...
1 vote
2 answers
433 views

Quick question regarding Larmor precession and bar magnets

So I was just reading a bit about magnetic dipole moments, Larmor precession, angular momentum etc., but there was one little thing that was bothering me. As far as I know, any angular momentum will ...
0 votes
4 answers
1k views

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 ...
1 vote
2 answers
581 views

Gyroscope precession and Euler equations

I've been trying for so long to solve this problem, but the solution I have found isn't the one I expected. Basically, I have to solve Euler's equations for a gyroscope with a weigth at a distance d. ...
0 votes
1 answer
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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 ...
3 votes
1 answer
53 views

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 ...
1 vote
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 ...
2 votes
0 answers
29 views

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/...
1 vote
1 answer
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Why is only one component of spin angular momentum considered in the precession of a top?

This was how the orbital angular velocity/ angular velocity of precession was shown to be calculated in my textbook ($\phi$ is angle made by top with vertical) $$dL=L_\text {spin}\sin\phi d\theta$$ ...
4 votes
2 answers
14k views

What causes precession or nutation in a spinning object?

What causes precession in a spinning object? What causes nutation in a spinning object? What causes a top, gyroscope, and the earth to wobble? Just because it's a simple question, I'm not expecting ...
2 votes
5 answers
668 views

Do protons and electrons actually precess?

I know that protons and electrons do not actually spin, although they have the property of spin. I was learning about MRI. I was introduced to the idea that you have the spin of the proton in the ...
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0 answers
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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 ...
0 votes
0 answers
29 views

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 ...
4 votes
2 answers
2k views

Will a precessing spinning wheel fall down if there is no friction at all?

If there where no friction at all, would a spinning wheel held up by one end of the axis spin precess forever without falling down? I just asked another question about the same problem: Direction ...
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1 answer
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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 ...
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0 answers
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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 {...
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 $\...
1 vote
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 ...
7 votes
3 answers
520 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
1 answer
293 views

Will a double gyroscope provide net upward force when rotated?

I watched this video on double gyroscope Precession: https://m.youtube.com/watch?v=vGun5athdfg When the two gyroscopes are spinning in the same direction, the apparatus can be rotated and the arms ...
1 vote
1 answer
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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 ...
3 votes
1 answer
132 views

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 ...
2 votes
1 answer
745 views

Precession of Angular momentum of Symmetric Top

For a torque free symmetric top, is the angular momentum in body fixed coordinates in same direction as instantaneous axis of rotation? I know that instantaneous axis of rotation precesses about ...
1 vote
0 answers
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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 ...
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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 ...
1 vote
1 answer
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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 ...
0 votes
1 answer
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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 ...
5 votes
2 answers
617 views

Infinite Larmor precession

Say an isolated electron (meaning it's not part of an atom) is at rest and we turn on a homogeneous magnetic field around it. The electrons' spin undergoes the Larmor precession (except in the case ...
1 vote
1 answer
174 views

Regarding nuclear magnetic resonance

In NMR experiment we provide an external radio frequency signal which will induce transition of nuclear spins to higher states,and then it returns to ground state precessing around the magnetic field ...
3 votes
1 answer
418 views

Precession of perihelion of Mercury?

I have a few questions about precession of Mercury and GR corrections. Feel free to any that you can: GR is used to correct precession caused by Sun on Mercury by time dilation and length contraction....
3 votes
5 answers
16k views

Direction of torque precession of a spinning wheel

Consider a spinning wheel, which is held up by one end of it's axis like this: To explain why the change of angular momentum is directed as shown in the figure above, one usually says that there is ...

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