Definition:Orbit (Physics)

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This page is about Orbit in the context of Physics. For other uses, see Orbit.


Let $A$ and $B$ be bodies in space.

The orbit of $A$ around $B$ is the path taken by $A$ as it travels around $B$ under the influence of the force acting between $A$ and $B$.

Period of Orbit

The period of the orbit is the length of time it takes for $A$ to travel once around $B$ and return to its original position.

Radius of Orbit

Let $\mathbf r$ be the position vector of the center of mass of $A$ with respect to the center of mass of $B$ at a particular point in time.

The radius of the orbit of $A$ around $B$ is defined as:

the position vector $\mathbf r$


the length of $\mathbf r$.

Context will determine which is meant.

Also see

  • Results about orbits in the context of physics can be found here.