# Rotation around a fixed axis

Special case of rotational motion.

- Rotation around a fixed axis294 related topics

## Centrifugal force

Inertial force that appears to act on all objects when viewed in a rotating frame of reference.

It is directed away from an axis which is parallel to the axis of rotation and passing through the coordinate system's origin.

## Angular velocity

In physics, angular velocity or rotational velocity ('''

Orbital angular velocity refers to how fast a point object revolves about a fixed origin, i.e. the time rate of change of its angular position relative to the origin.

## Right-hand rule

Common mnemonic for understanding orientation of axes in three-dimensional space.

In mathematics, a rotating body is commonly represented by a pseudovector along the axis of rotation.

## Precession

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.

## Nutation

Nutation is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight, or as an intended behaviour of a mechanism.

## Rigid body

Solid body in which deformation is zero or so small it can be neglected.

Two points of a rotating body will have the same instantaneous velocity only if they happen to lie on an axis parallel to the instantaneous axis of rotation.

## Center of mass

Unique point where the weighted relative position of the distributed mass sums to zero.

Typically, a human's center of mass is detected with one of two methods: the reaction board method is a static analysis that involves the person lying down on that instrument, and use of their static equilibrium equation to find their center of mass; the segmentation method relies on a mathematical solution based on the physical principle that the summation of the torques of individual body sections, relative to a specified axis, must equal the torque of the whole system that constitutes the body, measured relative to the same axis.

## Phonograph

Device for the mechanical and analogue recording and reproduction of sound.

While the cylinder was rotated and slowly progressed along its axis, the airborne sound vibrated a diaphragm connected to a stylus that indented the foil into the cylinder's groove, thereby recording the vibrations as "hill-and-dale" variations of the depth of the indentation.

## Polar motion

Motion of the Earth's rotational axis relative to its crust.

If the earth were perfectly symmetrical and rigid, M would remain aligned with its axis of symmetry, which would also be its axis of rotation.