Newton’s First Law of Motion: Inertia

Vocabulary and key concepts from Newton's First Law of Motion, covering historical perspectives, the property of inertia, force vectors, and equilibrium conditions.

Aristotle

An influential Greek philosopher who taught that elements consist of earth, water, air, and fire, and that motion is categorized as either natural or violent.

Natural Motion

A concept in Aristotelian physics where objects seek their proper and natural state without an external push or pull.

Violent Motion

A type of motion in Aristotelian physics that requires a sustained push or pull to occur.

Inertia

A property of matter that describes the tendency of an object to resist changes in its state of motion.

Galileo’s Inclined Planes

Experimental tools used by Galileo to effectively slow down a ball's changes in speed and observe the behavior of motion.

Galileo's Interpretation of Motion

A perspective that differed from Aristotle by emphasizing the rates of time rather than just distance or natural states.

Friction

An opposing force that causes objects, such as a hockey puck sliding across ice, to eventually come to rest.

Newton's First Law (Force in Outer Space)

In the absence of friction and air resistance, no force is required to keep an object sliding at a constant velocity.

Straight-line Path

The normal path a moving object follows when no external forces act upon it, such as Earth's hypothetical movement if gravity from the Sun vanished.

Vector Quantity

A quantity, such as force, that is defined by having both magnitude and direction.

Net Force

The vector sum of all forces acting on an object; for example, a $15\,N$ force left and a $5\,N$ force right result in a net force of $10\,N$.

Equilibrium Rule

Represented by the formula $\Sigma F = 0$, this rule applies to objects or systems at rest or in uniform motion in a straight line.

Mechanical Equilibrium

A state where an object is either at rest or moving with constant velocity, experiencing no changes in velocity.

Support Force

An upward force that balances the weight of an object on a surface; for a $10\,N$ book at rest on a table, this force is exactly $10\,N$.

Resultant Force

The magnitude of the net force acting on an object; for example, a $10\,N$ force northward and a $25\,N$ force southward result in a magnitude of $15\,N$.

Rope Tension

The force transmitted through a rope; in a tug-of-war where both sides pull with $400\,N$, the net force is zero but the tension is $400\,N$.