Newton's Laws of Motion - First Law

A collection of vocabulary terms and definitions regarding Newton's First Law of Motion, types of forces, and kinematic quantities like speed, velocity, and acceleration.

Inertia

The tendency of an object to resist changes in its motion or the resistance an object has to a change in its state of motion.

Newton's First Law of Motion

A law stating that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Law of Inertia

Another name for Newton's First Law of Motion.

Rest

The state of an object if it does not change its position with respect to its surroundings with time.

Motion

The state of an object if its position changes with respect to its surroundings and time.

Balanced Force

Forces of equal magnitude and in opposite directions that balance each other, resulting in an object being at equilibrium with no acceleration.

Equilibrium

The state of an object when all the forces acting upon it balance each other, meaning it will not accelerate.

Contact Forces

Interactions between objects that touch, such as applied force, spring force, drag force, frictional force, and normal force.

Non-contact Forces

Forces that attract or repel even from a distance, such as magnetic force, electric force, and gravitational force.

Unbalanced Force

A force that is not balanced by an opposite force of equal magnitude, causing an object's state of motion to change.

Distance

A scalar quantity that refers to "how much ground an object has covered" during its motion.

Displacement

A vector quantity that refers to "how far out of place an object is" and represents the object's overall change in position.

Speed

A scalar quantity that refers to "how fast an object is moving" or the rate at which an object covers distance.

Velocity

A vector quantity that refers to "the rate at which an object changes its position."

Acceleration

A vector quantity defined as the rate at which an object changes its velocity; an object accelerates if it changes its speed, direction, or both.

Constant Acceleration

A type of motion where an object's velocity changes by a constant amount each second.

Non-constant Acceleration

A type of motion where an object's velocity changes by a changing amount each second.

Net Force ($F_{net}$)

The vector sum of all the forces that act upon an object.