Physical Science Reference Sheet

Solid, liquid, gas

Think about ice, water, and steam

Plasma

It's superheated gas with charged particles

Physical changes alter form but not composition; chemical changes create new substances

Mass per unit volume (D = m/v)

It tells you how tightly packed matter is

They move faster and spread apart

A solid changing directly to a gas without becoming a liquid

Dry ice does this

An element is a pure substance of one type of atom; a compound is two or more elements chemically bonded

Two or more substances physically combined but not chemically bonded

100°C / 212°F

0°C / 32°F

Distance traveled per unit of time (speed = distance ÷ time)

Velocity includes direction; speed does not

The rate of change of velocity over time

It can be speeding up, slowing down, or changing direction

An object at rest stays at rest, and an object in motion stays in motion, unless acted upon by an external force

Also called the law of inertia

The tendency of an object to resist changes in its state of motion

Motion where gravity is the only force acting on an object

The maximum speed reached when air resistance equals the force of gravity

9.8 m/s² (approximately 10 m/s²)

Force = mass × acceleration (F = ma)

The equation is F = ma

For every action, there is an equal and opposite reaction

A force that opposes the motion of objects sliding against each other

The force of attraction between any two objects with mass

Newton (N)

Mass is the amount of matter (constant); weight is the force of gravity on that mass (varies by location)

When forces on an object are equal in size but opposite in direction, resulting in no change in motion

A force that acts toward the center of a circular path, keeping an object moving in a circle

Think of swinging a ball on a string

Mass times velocity (p = mv)

A heavy truck at high speed has a lot of this

In a closed system, total momentum before a collision equals total momentum after

The energy of motion (KE = ½mv²)

Stored energy due to position or condition

A ball at the top of a hill has this

Energy cannot be created or destroyed, only transformed from one form to another

Force applied over a distance (W = F × d)

The rate at which work is done (P = W/t)

Joule (J)

Watt (W)

Conduction, convection, and radiation

Heat transfer through direct contact between molecules

Touching a hot stove

Lever, wheel and axle, pulley, inclined plane, wedge, screw

A disturbance that transfers energy through matter or space

Transverse waves vibrate perpendicular to direction of travel; longitudinal waves vibrate parallel

The distance between two consecutive crests (or troughs) of a wave

The number of waves that pass a point per second, measured in Hertz (Hz)

Approximately 300,000 km/s (3 × 10⁸ m/s)

Approximately 343 m/s (about 767 mph)

Radio, microwave, infrared, visible light, ultraviolet, X-ray, gamma ray

When a wave bounces off a surface

The bending of a wave as it passes from one medium to another

This is why a straw looks bent in water

Its wavelength (or frequency)

The flow of electric charge (electrons) through a conductor

The electrical potential difference that drives current through a circuit (measured in volts)

Think of it as electrical 'pressure'

V = IR (Voltage = Current × Resistance)

Series: components in a single path; parallel: components in multiple branching paths

Conductors allow electricity to flow easily (metals); insulators resist flow (rubber, glass, plastic)

The area around a magnet where magnetic force is exerted

A magnet created by wrapping wire around an iron core and running electric current through it

The buildup of electric charge on a surface, caused by the transfer of electrons

Rubbing a balloon on your hair demonstrates this

Protons (positive), neutrons (neutral), electrons (negative)

In the nucleus (center)

The number of protons (atomic number)

An atom that has gained or lost electrons, giving it a net electric charge

Atoms of the same element with different numbers of neutrons

Atomic number (number of protons), with elements in groups by similar properties

A force of attraction that holds atoms together

A bond formed when atoms share electrons

A bond formed when one atom transfers electrons to another

Like NaCl (table salt)

How acidic or basic a solution is (0-14 scale, 7 is neutral)