Newton’s Laws of Motion & Related Concepts

Vocabulary flashcards summarizing key terms and principles about force, motion, and Newton’s three laws.

Force

A push, pull, or twist exerted on an object, usually resulting from an interaction between two objects.

Motion

The change in an object’s position; described by its speed and direction (velocity).

Acceleration

The rate at which an object’s velocity changes; produced when a net, unbalanced force acts on the object.

Inertia

An object’s resistance to any change in its state of motion (whether at rest or moving).

Newton’s First Law of Motion (Law of Inertia)

Objects at rest remain at rest, and objects in motion stay in motion at constant velocity unless acted upon by an unbalanced force.

Newton’s Second Law of Motion (Law of Acceleration)

The acceleration of an object with constant mass is proportional to the net force acting on it and occurs in the direction of that net force (summarized as F = m·a).

Newton’s Third Law of Motion (Law of Action and Reaction)

For every action force there is an equal-in-size, opposite-in-direction reaction force.

Net Force

The vector sum of all forces acting on an object; determines the object’s acceleration.

Balanced Forces

Forces that cancel each other so their vector sum is zero, causing no change in motion.

Unbalanced Forces

Forces whose vector sum is not zero, resulting in acceleration of the object.

Friction

A force that opposes motion between surfaces in contact, slowing or preventing movement.

Air Resistance

A type of friction that opposes the motion of objects moving through air.

Gravity

The attractive force between masses; on Earth it pulls objects downward, causing acceleration toward the ground (≈9.8 m/s²).

Isaac Newton

English scientist who formulated the three laws of motion and explained how forces like gravity govern the movement of objects.