law of motion
Definition of law of motion
1
: a statement in dynamics: a body at rest remains at rest and a body in motion remains in uniform motion in a straight line unless acted upon by an external force
— called also Newton's first law of motion
2
: a statement in dynamics: the acceleration of a body is directly proportional to the applied force and is in the direction of the straight line in which the force acts
— called also Newton's second law of motion
3
: a statement in dynamics: for every force there is an equal and opposite force or reaction
— called also Newton's third law of motion
Test Your Vocabulary
Challenging Words You Should Know
-
- Often used to describe “the march of time,” what does inexorable mean?

Test your vocabulary with our 10-question quiz!
TAKE THE QUIZ
A daily challenge for crossword fanatics.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridged
Share law of motion