Scientific Dictionary

An effect that pulls something closer.

An effect by which one thing is pulled toward another thing. If an object is pulled toward another object, that is a simple example of attraction.

Example: If an object is pulled toward another object, that is a simple example of attraction.

The middle point of a circle, equally distant from its edge.

Every point on a circle is the same fixed distance from its center. In a stone-on-a-rope example, the hand can mark the center.

Example: In a stone-on-a-rope example, the hand can mark the center.

The inward force that bends motion toward the center of a circle.

For circular motion, an object must keep changing direction. The net inward force that produces this turning is called centripetal force.

Example: The pull of a rope can provide centripetal force to a stone moving in a circle.

Motion along a circle or circular path.

In circular motion the object keeps moving while its direction changes continuously. A stone swung on a rope is a simple example.

Example: A stone swung on a rope is a simple example.

The way an object is moving at that moment.

The direction of motion tells which way the object is heading. Changing direction changes its path.

Example: An object moving east has an eastward direction of motion.

A push or pull that can change an object’s motion.

A force can make an object start, stop, speed up, slow down, or change direction. Pushing a box applies force to it.

Example: Pushing a box applies force to it.

The natural pull that makes objects move toward the Earth.

When an object is released, it moves toward the Earth. This pull is called gravity. The word is used to explain why everyday objects fall toward the ground.

Example: If you let go of an apple, it falls toward the ground.

The longest side of a right-angled triangle.

In a right-angled triangle, the side opposite the right angle is the hypotenuse. In the first source diagram, AC is the hypotenuse.

Example: In the first source diagram, AC is the hypotenuse.

An object’s tendency to resist a change in its motion.

An object tends to keep its present state: staying still if it is still, or continuing to move unless something acts on it. A book on a table does not start moving until it is pushed.

Example: A book on a table does not start moving until it is pushed.

Natural inclination is a body's supposed own tendency to move in a certain way.

In the book’s discussion, this means the direction or kind of motion a body is said to prefer by its own nature. It belongs to the older model being described. It should not automatically be treated as a standard modern physics term.

Example: If a body is said to tend toward one direction by itself, that is its natural inclination in this discussion.

Meeting another line at a right angle.

Two lines are perpendicular when they meet at a 90-degree angle. In the first diagram, AB is shown as perpendicular to CB.

Example: In the first diagram, AB is shown as perpendicular to CB.

“Power of centralization” is the source's name for a supposed built-in resisting power.

In the book model, this phrase names a supposed hidden power in a body that resists an imposed motion. It is the book’s own label. It should not automatically be treated as a standard modern physics term.

Example: The source says a body has a “power of centralization” that resists motion imposed on it.

Repulsion is the book model’s name for an effect or tendency that goes away from a pull or center.

Across these statements, repulsion is used for an away-going or outward effect. It belongs to the model being discussed in the book. It should not automatically be treated as one fixed modern physics force.

Example: If one effect pulls inward and another is described as tending away, the second is called repulsion in this discussion.

Resistance to motion means not easily following a motion being imposed.

In the book’s discussion, this describes a body not easily following a new motion imposed on it. The statements ask what explains that resistance. It should not automatically be treated as another name for modern inertia.

Example: If a body does not easily follow a newly imposed motion, the statement describes that as resistance to motion.

The motion of a body around another body or a central point.

A body follows a path around a center or another body. One complete revolution means one full round.

Example: A planet going around the center is called revolution here.

Movement along a path that does not bend.

Motion in which an object keeps moving along one straight path instead of turning to another direction. Moving straight down a straight road is a simple picture of straight-line motion.

Example: Moving straight down a straight road is a simple picture of straight-line motion.

The straight direction that just touches a circle at one point.

At a point on a circle, a tangent is a straight line that touches the circle there without following the curve. At the release point, the straight touching direction is the tangent direction.

Example: At the release point, the straight touching direction is the tangent direction.

The path a moving object follows.

When an object is thrown or fired, its whole route through the air is its trajectory. A bullet can move forward while its path bends downward.

Example: A bullet can move forward while its path bends downward.