Newton’s First Law
Reference from the original Physics I textbook.
- Newton’s First Law
In an inertial frame, an object remains at rest or moves with constant velocity when the net external force on it is zero.
- Related Glossary Terms
- Index
Reviewed physics notes (1)
These corrections keep the original lesson’s purpose while fixing errors in the source edition.
- It is net force, not the presence of any outside force, that changes motion. — Reference 1
Glossary and deeper reading · 1 refreshers
These editorial refreshers supplement the reading. Definitions and examples are added guidance; original source wording and recorded answers remain in their original context.
-
Force
A force describes an interaction that can change an object’s momentum. It is a vector measured in newtons, so both size and direction matter when forces are added. For example, a rope can pull a cart while the floor exerts friction in another direction.