# Rigid-Body Motion

### How does a rigid body move?

A rigid body may move in pure translation, pure rotation or in general planar motion.

A particle can only translate and is described by its position, velocity and acceleration. A rigid body, in addition to translating, may also rotate. A rigid body is described by both linear and angular position, linear and angular velocity, and linear and angular acceleration.

#### Compare and contrast the linear and angular versions of the following equations.

Rotational Equations | Translational Equations |
---|---|

ω = dθ/dt | v = ds/dt |

α = dω/dt | a = dv/dt |

α dθ = ω dω | a ds = v dv |