Newton's first law of motion ↩

aliases: [Newton's 1st law, Newton's 1st law of motion, Newton's first law, Newton I.]
shorthands: {}
created: 2022-06-16 00:22:25
modified: 2022-06-23 23:52:40

Every body continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it.

This lay expresses the principle of inertia: the natural behavior of a body is to move in a straight line at constant speed. In the absence of outside influences, a body's motion preserves the status quo.

In mathematical terms, this could be formulated the following way: If there is no force acting on a body, its velocity remains constant:

Inertial frames

A frame of reference, where Newton's first law is true, is an inertial frame.

All inertial frames are equivalent, meaning the none of them have any privilege over the others.