Science vocab + equations

Reference point

is the starting point you choose to describe the location, or position, of an object

Position

is an object's distance and direction from a reference point

Motion

is the process of changing position

Displacement

is the difference between the initial (first) position and the final position of an object

Speed

is a measure of the distance an object travels per unit of time

constant speed

is the rate of change of position in which the same distance is traveled each second

instantaneous speed

is speed at a specific instant in time

Average speed

is the total distance traveled divided by the total time taken to travel that distance

Velocity

is the speed and the direction of a moving object

Acceleration

is a measure of the change in velocity during a period of time

force

a push or pull on an object

contact force

is a push or a pull on one object by another that is touching it

non contact force

a force that one object can apply to another object without touching it

Gravity

is an attractive force that exists between all objects that have mass

mass

the amount of matter in an object(kg)

weight

is the gravitational force exerted on an object

friction

is a force that resists the motion of two surface that are touching

4 types: static, sliding, fluid, rolling

The types of friction

net force

The combination of all forces acting on an object

balanced forces

forces acting on an object that combine and form a net force of zero

unbalanced forces

forces acting on an object that combine and form a net force that is not zero

Newton's First Law

if the net force on an object is zero, the motion of the object does not change

Inertia

The tendency of an object to resist a change in motion

Newton's Second Law

the acceleration of an object is equal to the net force acting on it divided by the object's mass

circular motion

is any motion in which an object is moving along a curved path

centripetal force

in circular motion, a force that acts perpendicular to the direction of motion, toward the center of the curve

Newton's Third Law

when one object exerts a force on a second object, the second object exerts an equal force in the opposite direction on the first object

force pair

is the forces two objects apply to each other

momentum

is a measure of how hard it is to stop a moving object

momentum\=mass x velocity

Momentum equation

Law of Conservation of momentum

the total momentum of a group of objects stays the same unless outside forces act on the objects

fluid

is any substance that can flow and take the shape of the container that holds it

pressure

is the amount of force per unit area applied to an object's surface

atomspheric pressure

the ratio of the weight of all the air above you to your surface area

buoyant force

is an upward force applied by a fluid on an object in the fluid

Archimedes' Principle

the weight of the fluid that an object displaces is equal to the buoyant force acting on the object

Pascal's Principle

states that when pressure is applied to a fluid in a closed container, the pressure increases by the same amount everywhere in the container

Bernoulli's Principle

states that the pressure of a fluid decreases when the speed of that fluid increases

drag force

is a force that opposes the motion of an object through a fluid

wave

is a disturbance that transfers energy from one place to another without transferring matter

mechanical wave

a wave that can travel only through matter

transverse wave

is a wave in which the disturbance is perpendicular to the direction the wave travels

crests

the highest points on a transverse wave

troughs

the lowest points on a transverse wave

longitudinal wave

makes the particles in a medium move parallel to the direction that the wave travels

compressions

the region of a longitudinal wave where the particles in the medium are the closet together

rarefactions

the regions of a longitudinal wave where the particles are farthest apart

electromagnetic wave

a wave that can travel through empty space and through matter

amplitude

of a wave is the maximum distance that the wave moves from its rest position

Wavelength

of a wave is the distance from one point on a wave to the same point on the next wave

frequency

of a wave is the number of wavelengths that pass by a point each second

what is formula for calculating wave speed

\= frequency x wavelength

absorption

is the transfer of energy by a wave to the medium through which it travels

Transmission

is the passage of light through an object such as windows

law of reflection

when a wave is reflected from a surface, the angle of reflection is equal to the angle the incidence

refraction

is the change in direction of a wave that occurs as the wave changed speed when moving from one medium to another

Diffraction

the change in direction of a wave when it travels by the edge of an object or through an opening

interference

occurs when waves overlap and combine to form a new wave

sound waves

longitudinal waves that can only travel through matter

longitudinal wave

is a wave that makes the particles in the material that carries the wave move back and forth along the direction the ave travlesz

vibration

is a rapid, back and forth motion that can occur in solids, liquids, or gases

medium

a material in which a wave travels

Compression

region of a longitudinal wave where the particles of the medium are closest together

Rarefaction

is a region of longitudinal wave where the particles are farthest apart

Amplitude

is the maximum distance the particles in a medium move from their rest positions as the wave passes through a medium

Wavelength

the distance between a point on one wave and the same point on the next cycle of the wave

Intensity

is the amount of sound energy that passes through a square meter of space in one second

Frequency

the number of waves that pass a given point per second

pitch

the perception of how high or low a sound seems

Doppler effect

the change of pitch when a sound source is moving in relation to an observer

resonance

increase of amplitude that occurs when an object vibrating at its natural frequency absorbs energy from a near by object vibrating at the same frequency

echolocation

the process an animal uses to locate an object by means of reflected sounds

sonar

a system that uses the reflection of sound waves to find underwater objects

electromagnetic waves

a wave that can travel through empty space and through matter

radiant energy

energy carried by an electromagnetic wave

electromagnetic spectrum

is the entire range of electromagnetic waves with different frequencies and wavelengths

radio wave

a low-frequency, low-energy electromagnetic wave that has a wavelength longer than about 30 cm

microwave

is a low frequency, low energy electromagnetic wave that has a wave between 1mm and 30 cm

ultraviolet wave

is an electromagnetic wave that has a slightly shorter wavelength and higher frequency than light and carries enough energy to cause chemical reactions

x-ray

is a high-energy electromagnetic wave that has a slightly shorter wavelength and higher frequency than an ultraviolet wave

gamma ray

is a high-energy electromagnetic wave with a shorter wavelength and higher frequency than all other types of electromagnetic waves

light

is electromagnetic radiation that you can see

Reflection

is the bouncing of a wave off a surface

transparent

a material that allows almost all of the light striking it to pass through, and through which objects can be seen clearly

translucent

a material that allows most of the light that strikes it to pass through, but through which objects appear blurry

opaque

a material through which light does not pass

law of reflection

angle of incidence \= angle of reflection

regular reflection

reflection of light from a smooth, shiny surface

diffuse reflection

reflection of light from a rough surface

concave mirror

A mirror that curves inward

focal point

the point at which rays parallel to the optical axis reflect and meet

convex mirror

A mirror with a surface that curves outward (spoon)

lens

is a transparent object with at least one curved side that causes light to change direction

convex lens

A lens that is thicker in the middle than at the edges

concave lens

a lens that is thicker at the edges than the middle

rod

responds to low light

cone

respond to color

retina

absorbs light

iris

controls the pupil's size

pupil

lets different amount of light in eyes