Science Final

transverse wave

A wave in which the particles of the medium move perpendicularly to the direction the wave is traveling

longitudinal wave

a wave in which the particles of the medium vibrate parallel (same) to the direction of wave motion

Frequency

the number of complete wavelengths that pass a point in a given time

Hertz (Hz)

Unit of measurement for frequency

Amplitude

Height of a wave

Wavelength

The distance between two corresponding parts of a wave

Speed of Light

300,000,000 m/s

Speed of Sound

340 m/s

Crest

the highest point of a transverse wave

Trough

the lowest point of a transverse wave

Plane Waves

waves that move in straight lines

Circular Waves

Waves that originate from one point and move in all directions

Reflection

the bouncing back of a ray of light, sound, or heat when the ray hits a surface that it does not go through

Refraction

the bending of a wave as it enters a new medium at an angle

Absorption

when the amplitude of a wave gets smaller as the wave enters into a substance.

Diffraction

The bending of a wave as it moves around an obstacle or passes through a narrow opening

decibles

A unit used to measure the loudness of a sound.

pitch

the highness or lowness of a sound

Sound Waves

a longitudinal wave consisting of compressions and rarefactions, which travels through a medium

medium

Material through which a wave travels

natural frequency

the frequency at which an object vibrates when it is disturbed (aka: fundamental, first harmonic)

Resonance

A phenomenon that occurs when two objects naturally vibrate at the same frequency (amplifies the sound)

standing wave

a wave that appears to stand in one place, even though it is really two waves interfering as they pass through each other

Harmonics

frequencies that are multiples of fundamental frequency

Node

A point on a standing wave that has very little to no motion

Antinode

a point of maximum displacement (amplitude) midway between two nodes in a standing wave

constructive interference

The interference that occurs when two waves combine to make a wave with a larger amplitude

destructive interference

The interference that occurs when two waves combine to make a wave with a smaller amplitude

Physical Model

Models that are made of materials and that can be touched and measured

conceptual model

A verbal or written explanation on how something worked, or why something occurred

mathematical model

Shows a relationship between two variables.

independent variable

the variable that is manipulated by the researcher. Placed on x-axis

dependent variable

a variable (often denoted by y ) whose value depends on that of another.

inverse relationship

a relationship in which one variable decreases when another variable increases

direct relationship

a relationship in which one variable increases with an increase in another variable

position

an object's distance and direction from a reference point

distance

How far an object moves

slope of a position vs time graph

speed

average speed

The overall rate of speed at which an object moves; calculated by dividing the total distance an object travels by the total time.

instantaneous speed

The rate at which an object is moving at a given moment in time

Acceleration

rate of change of velocity; can be calculated by dividing the change in the velocity by the time it takes the change to occur

positive acceleration

an increase in velocity

negative acceleration

decrease in velocity

no acceleration

constant velocity

free fall acceleration

acceleration due to gravity

acceleration due to gravity

9.8 m/s/s

Slope of Velocity vs. Time

acceleration

speed equation

distance (d) / time (t)

Speed of this position vs time graph

zero

Acceleration of B on this velocity vs time graph

constant

Temperature

A measure of the average energy of motion of the particles of a substance.

thermal energy

total amount of energy in an object; is dependent on temp. and mass

Conductors

materials through which heat can easily flow

Absorbers

Substances that are able to take in heat and effectively give off heat

dark clothing or objects

absorbers

heat

The energy transferred between objects that are at different temperatures

convection current

the movement of a fluid, caused by differences in temperature, that transfers heat from one part of the fluid to another

Radiation

Energy that is radiated or transmitted in the form of rays or waves or particles.

Emitters

Objects that are good absorbers of radiation are good ____ as well

sunlight or heat coming off a warm object

radiation

thermal expansion

the expansion of matter when it is heated

liquid thermometer

uses the expansion of a liquid in a thin tube to indicate the temperature

heat

always flows from hot to cold

from inside to outside

if a door is open during these cold days heat would flow from

thermal equilibrium

The state of two or more objects or substances in thermal contact when they have reached a common temperature

winds on earth

example of convection

Reflectors

a surface designed to redirect light or heat to another surface

Insulators are

materials that keeps energy such a electricity, heat or cold from easily transferring through.

air and water

examples of insulators

Metals

good conductors of heat and electric current

characteristics of conductors

dense and free electrons

Acid

any compound that forms H+ ions in solution

Base

a compound that produces hydroxide ions in solution

slippery

base

bitter taste

base

turn litmus paper blue

base

pH scale

scale with values from 0 to 14, used to measure the concentration of H+ ions in a solution

strong acid

an acid that ionizes completely in a solvent

weak acid

an acid that releases few hydrogen ions in aqueous solution

strong base

a base that completely dissociates into metal ions and hydroxide ions in aqueous solution

weak base

A base that does not dissociate completely into ions in solution.

sour taste

acid

change litmus paper red

acid

Our blood is considered to be _.

neutral (7.4 pH)

Cleaning products are very __.

basic (alkaline)

pH 0-6

acid

pH 8-14

base

pH 7

neutral

neutralize

When an acid and a base combine changing the pH to be neutral and often produce an ionic compound and water.

salt

An ionic compound made from the neutralization of an acid with a base.

indicator

A compound that changes color in the presence of an acid or a base

polar molecule

A molecule that has electrically charged areas.

hydrogen bonds in water

They exert an attractive force strong enough so that water clings

hydrogen bonds

Very weak bonds; occurs when a hydrogen atom in one molecule is attracted to the electrostatic atom in another molecule

Solutions are

homogeneous mixtures at the molecular level

Solutions

A mixture where substances are distributed evenly. Has a solvent & solute.

Alloys

mixtures of two or more metals

Colloids

particles that are intermediate in size between those in solutions and suspensions

Suspensions are

heterogeneous mixtures

suspensions

type of mixture with insoluble compounds, that eventually settle upon standing, muddy rivers are an example