What is Precession: Definition and 258 Discussions

Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In other words, if the axis of rotation of a body is itself rotating about a second axis, that body is said to be precessing about the second axis. A motion in which the second Euler angle changes is called nutation. In physics, there are two types of precession: torque-free and torque-induced.
In astronomy, precession refers to any of several slow changes in an astronomical body's rotational or orbital parameters. An important example is the steady change in the orientation of the axis of rotation of the Earth, known as the precession of the equinoxes.

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  1. W

    Why spinning protons have precession under magnetic field?

    And this phenomenon also occurs in neutrons?
  2. F

    Why does a gyroscope maintain a constant angular momentum during precession?

    Precession for me is one of the most confusing and interesting concepts in physics so far, I've thought about it a lot and I still don't have it all figured out. Here's an interesting question: Consider a gyroscope that has the axle in a horizontal position and spinning so that the angular...
  3. M

    Exploring Precession of the Equinoxes & Zodiac Signs

    i know many of the viewers will disregard this message, but to anyone out there who is knowledgeable in ancient wisdom i humbly ask: regarding astrology from a scientific perspective, i understand that the tilt of the Earth is changing approximately 1 degree per 70 years, and this in turn...
  4. C

    How Does Gyroscopic Precession Relate to Torque and Angular Momentum?

    hi. not sure if this belongs in here, so sorry in advance for any trouble caused. i am in a bit of a predicament with a physics assessment of mine; i need to know the mathematical relationships between the precessional frequency, the couple (or torque, as i have read it called) and the angular...
  5. A

    Precession of a spinning projectile, other dynamics problems

    Ok, I'm using Beer and Johnston's engineering Mechanics/Dynamics book for class, and i don't particularly enjoy it's lack of explanation for the following problem: The graphic shows a bullet flying to the right with the x coordinate pointing along its long axis and the y-axis perpendicular...
  6. Andre

    Understanding the Effects of Earth's Precession on Planet Cores | Crystalinks"

    We know that the Earth is precessing. http://www.crystalinks.com/precession.html We also know that the Earth has a fluid outer core and a solid inner core. How would the core(s) react on that precession movement?
  7. T

    Precession of the perihelion of Mecury

    My problem involves the precession of the perihelion of Mecury F sub g = - (GMm)/r^2 * (1 + a/r) where a << r I proved in previous parts d^2r/dt^2 - r*(dtheta/dt)^2 = -GM/r^2 * (1 + a/r) [eqn 1] and r* d^2theta/dt^2 + 2*dr/dt*dtheta/dt = 0 I also used u(theta) = 1/r(t) to turn eqn 1 to...
  8. Andre

    Precession betrays Nemesis position?

    In 1995 Richard Muller et al proposed the existence of a twin star of the sun, Nemesis. This would expain the cyclic mass extinctions. To date there seems to be little substantiation for the existence of Nemesis and the only remaining option is: find it. That may be happening here...
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