Newton’s First Law: Why Objects Resist Change in Motion

Newton’s First Law is often called the Law of Inertia—objects naturally resist changes to their state of motion.
An object at rest stays at rest unless acted on by an unbalanced force like a push or pull.
An object in motion keeps moving at the same speed and direction unless something interferes.
Inertia depends on mass—the greater the mass, the harder it is to change the object’s motion.
This law explains why seatbelts are vital—your body keeps moving forward when a car suddenly stops.
Friction and air resistance are everyday forces that prevent motion from continuing forever.
In deep space, without friction, a spacecraft could glide in motion for millions of miles.
The law was a revolutionary shift from Aristotle’s belief that motion required continuous force.
Newton’s First Law is the foundation for understanding more complex motion and dynamics.
Everyday examples—like sliding a book across a table—show inertia at work in simple, relatable ways.