# Questions tagged [precession]

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I want to analyze the following system, where the mass of the axle is negligible and the Wheel is spinning. In particular I need to calculate the amount of torque about the point where the string ...
192 views

### How do I calculate the energy density of a flywheel rotating along dual axes?

It seems to me that if you can rotate a flywheel along more than one axis simultaneously you can significantly add to the amount energy it can store. So a flywheel that is spinning and precessing(?) ...
3k views

### Minimum speed needed for a gyroscope to precess

I was reading about gyroscopes and their precession. Based on the text, the angular speed of precession is: $\omega_{precession}=\dfrac{\tau}{L}$ But intuitively, if the wheel of the gyroscope is ...
27 views

### micron sanding apparatus [closed]

I am in need to shave a special material (composite much like fiberglass/kevlar) from 30 microns down to 10 microns, on a consistent basis. How would I make something like this? or is there anything ...
610 views

### Can precession happen with no external forces?

I wanted to ask the following question: Can a body that experiences no forces whatsoever precess? Let's say I have a body in space - no gravity or anything - can I make it precess without applying ...
409 views

### Can/Does angular momentum apply a torque?

Context I'm a psychologist and I'm interested in perception of gyroscopic forces. For that reason, I'm having to think about many of the classic issues relating to gyroscopes in reverse. That is, ...
447 views

### Where did Paul Gerber go wrong in arriving at the same equation as Einstein in explaining the Mercury anomaly?

We know that Einstein admitted that Paul Gerber's 1898 formula explaining the anomaly of Mercury's perihelion was the same as his own. Reportedly Gerber had made a mistake somewhere, so - even though ...
4k views

### What happens to orbits at small radii in general relativity?

I know that (most) elliptic orbits precess due to the math of general relativity, like this: source: http://en.wikipedia.org/wiki/Two-body_problem_in_general_relativity I also know that something is ...
582 views

### Mercury's precession

I read in an article about Mercury's precession that Newton's law of gravitation predicts such precession of planets ;but fails to caluclate the precession of Mercury.But most of popular science ...
896 views

### How to express a Spin Up in direction $\boldsymbol{\hat n}$ in terms of the $S_z$ basis

So, In the question below, they've asked me to express the Spin Up in n Vector in terms of the $S_z$ basis. As shown in the question, the unit vector for $\boldsymbol{\hat n}$ is expressed as a ...
1 vote
298 views

### What causes certain spinning tops to flip? [duplicate]

Certain spinning tops flip upside-down once spun sufficiently high, as shown in this video. Suppose I have the following: A cylindrically-symmetric top The principal axes of a given top's moment of ...
2k views

### What is radial oscillation and how is it measured?

In the context of the Earth orbiting the sun, the question of the problem is "If the radial oscillation has a higher frequency than the time it takes the Earth to orbit the sun, will the aphelion ...
1k views

### Mercury's perihelion precession [closed]

i want to plot the precession of mercury's perihelion in MatLaB .(like the image below).Help me out here ,guys. https://en.wikipedia.org/wiki/Apsidal_precession#/media/File:Perihelion_precession.svg ...
29 views

### Is Gyroscopic precession relative to the object in precessions axis of movement when there is drag imposed on the disc?

Does my question make sense? I am referring to the disc of an AutoGyro aircraft. Though the fuselage of a modern pusher AutoGyro will weather vane into the wind, the disc that provides lift does not. ...
867 views

### 3 Axis Gyroscope with forced Precession and Limits of Motion

I am working a problem concerning a 3 axis gryoscope, the spinning mass is a magnet (dipole). This is part of a optical sensing device. The inner gimbal is for pitch rotation, and the outer gimbal is ...
2k views

### When an electron orbits in a magnetic field, how exactly does its spin precess?

In the case of a cyclotron, with a constant magnetic field $B$ in the vertical direction, a moving electron circles in a horizontal orbit. The cyclotron frequency is $\omega = eB/m$. At the same ...
2k views

### How to tell if an orbit is closed given the potential?

I'm working on a homework question in which I am supposed to discuss the types of motion that orbits may have under a certain potential. What I've done so far is draw the energy diagram for such a ...
42 views

### How would spin of a binary depend on its mass?

I have been reading an article about a code that uses precession analysis on spin of binaries. At the beginning of the article authors describe units of code where they take $c=1$ (speed of light) and ...
1 vote
72 views

### Does Earth's precession rate change with the seasons?

As Earth's precession is caused by the differential solar, etc., attraction to its 'spare tire', then does the rate go to ~zero at the equinoxes and ~twice the average at the solstices? (preferred ...
1 vote
168 views

### Why does gravitational torque on a precessing gyroscope turn the spin momentum instead of making the gyroscope fall?

I read in a physics book that given the spin momentum is high the torque will turn the spin angular momentum instead of making the pendulum fall. What law governs this??
989 views

### Which force acts as centripetal force on gyroscope?

I think I have understood gyroscope in terms of angular momentum and how the torque of gravitational force moves it the way it does. Also I understand the direction in which it would move: What ...
429 views

### Reasoning behind predicting a gyroscopes motion

Lets say we have a gyroscope that has a flywheel spinning with constant angular velocity. The gyroscope is held in place in a position where the massless metal rod connecting to the flywheel is ...
2k views

### Understanding the operation of Thomas precession

How can we physically understand the operation of Thomas Precession? Thomas Precession is an effect that modifies the effective energy of coupling between the spin and the orbital angular momentum ...
143 views

### How would I explain why a top wobbles to someone who has never taken a physics course?

I found this this website that explains the precession of a top, but obviously, it is not comprehensible to a younger student. I am not referring to why tops stay up, just why they make circles that ...
914 views

### $LS$-coupling vector model precession?

In $LS$-coupling it is said (e.g. here, link to Google Books1) that in the $LS$-coupling scheme the individual $\vec l_i$ precess around $\vec L$ and the individual $\vec s_i$ precess around $\vec S$. ...
1 vote
189 views

### How is the precession rate of planets calculated? For which planets do we know the precession rates?

From what I've read, precession rates of Earth, Mars and Moon are known. Why is that? And how is it calculated?
62 views

### How to calculate precision of Pound-Drever-Hall technique?

When I read the fifth section (Noise and fundamental limits: how well can you do?) of Eric's article, I have question. In this section(page 85 and 86), Eric discussed the shot noise, and gave the ...
565 views

### Why is the centre of Earth's axial precession perfectly perpendicular to the ecliptic? (is it?)

It is my understanding that the Earth's axial precession is such that the line of the North pole pointing away from the planet traces out a circle on the celestial sphere with a period of roughly 26,...
2k views

### What is the difference between precession and axial tilt?

Am I right that the difference is that precession indicates the direction of the inclination of Earth's axis and the tilt is the quantity of this inclination? So that when there is no tilt there can't ...
298 views

### Imperfect circular orbit

At Arnold's classical mechanics book on page 40 he introduced the following problem: PROBLEM. At the entry of a satellite into a circular orbit at a distance 300 km from the earth the direction of ...
114 views

### Angular velocity in Euler's equations (Rigid body)

I was confused at something... Look at these equations: https://en.wikipedia.org/wiki/Euler%27s_equations_(rigid_body_dynamics) From what I understood the way we get them is by going into rotating ...
217 views

### Can there be precession without angular momentum?

In a wikipedia article it is said: The magnetic moment has a close connection with angular momentum called the gyromagnetic effect. This effect is expressed on a macroscopic scale in the ...
1 vote
183 views

### Motor-powered gyroscope's precession speed

I was doing experiment about the gyroscope's precession speed and I made my own gyroscope, which is the one in the picture. It is the motor-powered gyroscope as I found out the one made with bearing ...
6k views

### What is the physics of a spinning coin?

When we spin a coin on a table, we observe 2 things: It slows down and stops after sometime. It does not stay at just one point on the table but its point of contact with table changes with time. I ...
1k views

### Are elliptical orbits really elliptical?

I have wondered for a long time how elliptical orbits can work. It seems awkward for a freely-moving object to come very close to a source of gravity and then return to the exact point where it ...
1k views

### Details of Newtonian Prediction for Mercury's Precession

Could anyone point me to a book or outline the methods used to actually calculate the 532 arcseconds per century that Newtonian theory apparently predicts for Mercury's precession. I am completely ...
1 vote
71 views

### Finding the Mass of a Precessing Top

Consider a symmetric, non-nutating precessing top with one point fixed (the tip if you will). It's symmetry axis is at an angle $\theta$ to the vertical and it steadily precesses at some angular ...
735 views

### How to explain gyroscopic precession in a more intuitional way?

When Studying the phenomenon of precession a classic example installation is this: a wheel spins around the Y axis, gravity applies and the upper part starts spinning around the Z axis. The textbook ...
647 views

### Proof derivative of a vector following precession motion

I do not get some points of this proof about the time derivative of a unit vector $\hat{u}$ (costant magnitude) which is following a precession motion. The picture is the following. I want to prove ...
57 views

### Lense-Thirring Precession of short GRBs

Stone et al. 2014 have proposed that the jet resulting from the merger of a black hole (BH) and neutron star (NS) may precess due to Lense Thirring torques A large rotating mass e.g. the Earth, can ...
1k views

### Reaction to gyroscopic force [duplicate]

Just like the reaction of the weight of a body is a force acting on Earth towards the body, where and in what direction does the reaction of a gyroscopic force act?
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### What kind of torques cause an object to precess? [closed]

In studying precession, my textbook (Taylor's Classical Mechanics) makes the assumption that a top spinning about its symmetric axis, but tipped at an angle $\theta$, will precess nicely so long as ...
269 views

### How to obtain Thomas Precession from lie algebra of the Lorentz group? [closed]

it seems to be possible that you can get the Thomas Precession just through the commutation relations of the Lorentz group. With Thomas Precession i mean, that in general the product of two boosts is ...
1 vote
57 views

### Gyroscopic precession force translated 90 degrees? [duplicate]

I was watching a video on propeller gyroscopic effect, please take a look at this 1 minute segment (up to 6:06): https://youtu.be/QGWbjGqmoWo?t=307 Alternatively, here is a summarizing image from ...
281 views

### Earth precession

I got a bit confused while studying the tropical and sidereal years. I noticed that the Earth's precession is in the opposite direction than that of a top's precession, when their rotational direction ...
1k views

### Without using rotational mechanics, why does a gyroscope precess the direction it does?

When a top is spun, it will precess in some direction, either clockwise or counterclockwise. It's possible to find out which way using $\boldsymbol{\tau} = d\mathbf{L}/dt$ and \$\boldsymbol{\tau} = \...
992 views

### How was the neutron's spin measured?

In 2012 it was asked, How to measure the spin of a neutral particle. I'm not sure that the answer "Neutron spin can be measured in a Stern Gerlach setup." was really carried out. So what for ...
148 views

### Differential precession due to gravitational waves

To motivate the question, Andy Strominger recently put out a paper on calculating the Sagnac shift of counterrotating beams due to the angular momentum flux of a passing gravitational wave. See here:...