Section: STEM · PhysicsDifficulty: Easy
Newton's First Law
USUK
An object at rest stays at rest unless acted upon by an external force.
Also: law of inertia
Definition
Newton's First Law of Motion, also called the law of inertia, states that an object will remain at rest or move in a straight line at constant velocity unless acted upon by a net external force. This principle explains why passengers lurch forward when a car brakes suddenly. It forms the foundation of classical mechanics.
Example
“A hockey puck sliding on frictionless ice continues moving in a straight line indefinitely until it hits a wall or another force acts on it.”
Synonyms
- law of inertia
- first law of motion
- principle of inertia
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Related Terms
- Newton's Second Law
- Newton's Third Law
- Inertia
- Force