Commonly Used Words. Arranged alphabetically, these sections include spelling, usage, punctuation and capitalization notes for specific words and phrases commonly used in the CSU. An entry without an explanation is simply to indicate the correct spelling of a word or words. A B-C D-F G-M N-S T-Z.
Noun. 1. Newton's first law of motion-a body remains at rest or in motion with a constant velocity unless acted upon by an external force. first law of motion, Newton's first law. law of motion, Newton's law, Newton's law of motion-one of three basic laws of classical mechanics.
The first law of motion postulates the existence of at least one frame of reference called a Newtonian or inertial reference frame, relative to which the motion of a particle not subject to forces is a straight line at a constant speed. Newton's first law is often referred to as the law of inertia.