Pre-Lecture Vocabulary: Motion, Inertia, and Early Cosmology (Chapter 2)

A set of vocabulary flashcards covering key concepts from the pre-lecture notes on motion, Aristotle's ideas, Galileo's experiments, inertia, forces, and Newton's first law.

Geocentric theory

Earth-centered model in which Earth is at rest and all celestial bodies orbit it.

Heliocentric theory

Sun-centered model where planets (including Earth) orbit the Sun.

Ptolemy

Ancient astronomer who advocated the geocentric model and celestial spheres.

Copernicus

Astronomer who proposed the heliocentric model and challenged Ptolemy.

Galileo

Proponent of Copernican theory; challenged Aristotle and developed experiments supporting inertia.

Aristotle's natural motion (terrestrial)

Vertical motion toward an object's natural place on Earth (up for some, down for others).

Aristotle's natural motion (celestial)

Circular motion of celestial bodies around the center.

Aristotle's violent/imposed motion

Motion produced by external force that must be maintained to continue motion.

Four elements

Earth, Water, Air, Fire—the basis for Aristotle's natural motion and place.

Natural motion (terrestrial)

Vertical motion on Earth (upward for some elements, downward for others).

Natural motion (celestial)

Circular motion for objects in the celestial realm.

Inertia

Property of matter resisting changes in motion; not a force.

Mass

Amount of matter; a measure of inertia; stays constant; measured in kilograms.

Force

Push or pull that can cause a change in motion.

Net force

Sum of all forces acting on an object; determines acceleration.

Gravitational force

Force of gravity pulling objects toward Earth's center.

Newton's First Law (Law of Inertia)

An object at rest stays at rest and an object in motion stays in uniform straight-line motion unless acted on by a net external force.

Friction

Opposition to motion between contacting surfaces.

Normal (support) force

Perpendicular upward force exerted by a surface on an object.

Speed

Rate of motion; magnitude only (scalar).

Velocity

Speed with direction; a vector quantity.

Acceleration

Rate of change of velocity over time.

Equilibrium

State in which the net force on an object is zero; no change in motion.

Air resistance

Frictional force from air opposing motion through it.

Geocentric theory

Earth-centered model in which Earth is at rest and all celestial bodies orbit it.

Heliocentric theory

Sun-centered model where planets (including Earth) orbit the Sun.

Ptolemy

Ancient astronomer who advocated the geocentric model and celestial spheres.

Copernicus

Astronomer who proposed the heliocentric model and challenged Ptolemy.

Galileo

Proponent of Copernican theory; challenged Aristotle and developed experiments supporting inertia.

Aristotle's natural motion (terrestrial)

Vertical motion toward an object's natural place on Earth (up for some, down for others).

Aristotle's natural motion (celestial)

Circular motion of celestial bodies around the center.

Aristotle's violent/imposed motion

Motion produced by external force that must be maintained to continue motion.

Four elements

Earth, Water, Air, Fire
is the basis for Aristotle's natural motion and place.

Natural motion (terrestrial)

Vertical motion on Earth (upward for some elements, downward for others).

Natural motion (celestial)

Circular motion for objects in the celestial realm.

Inertia

Property of matter resisting changes in motion
is not a force.

Mass

Amount of matter; a measure of inertia; stays constant; measured in kilograms.

Force

Push or pull that can cause a change in motion.

Net force

Sum of all forces acting on an object; determines acceleration.

Gravitational force

Force of gravity pulling objects toward Earth's center.

Newton's First Law (Law of Inertia)

An object at rest stays at rest and an object in motion stays in uniform straight-line motion unless acted on by a net external force.

Friction

Opposition to motion between contacting surfaces.

Normal (support) force

Perpendicular upward force exerted by a surface on an object.

Speed

Rate of motion; magnitude only (scalar).

Velocity

Speed with direction; a vector quantity.

Acceleration

Rate of change of velocity over time.

Equilibrium

State in which the net force on an object is zero; no change in motion.

Air resistance

Frictional force from air opposing motion through it.

Newton's Second Law of Motion

The acceleration of an object is directly proportional to the net force acting on it, and inversely proportional to its mass, given by the formula \vec{F}_{net} = m\vec{a}.

Newton's Third Law of Motion

For every action, there is an equal and opposite reaction.

Weight

The force of gravity acting on an object's mass; calculated as W = mg, where m is mass and g is the acceleration due to gravity.

Terminal Velocity

The constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration; occurs when the net force is zero due to air resistance balancing gravitational force.