8th grade Science GMAS Review

speed

the rate of change of position (distance per time or d/t)

velocity

speed with direction

acceleration

the rate of change of velocity (velocity per time)

mass

quantity of matter (inertia)

weight

gravitational force

inertia

tendency to continue at rest or with constant velocity (mass or laziness)

If distance is 800 m and time is 200 s, what is speed?

4 m/s

friction

opposes motion

force

a push or pull ( changes the motion of object) measured in newtons

Newton's First Law

states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.

Newton's Second Law

(F=ma)states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object.

gravity

attraction between any two objects

Newton's Third Law

For every action, there is an equal and opposite reaction

kinetic energy

energy in the form of motion (1/2 mv²)

potential energy

energy stored due to position

chemical potential energy

energy stored in chemical bonds

gravitational potential energy

energy stored by object's above earth's surface (mgh)

mechanical energy

potential energy + kinetic energy

Law of Conservation of Energy

energy cannot be created or destroyed

energy

the ability to cause change (do work)

thermal energy

the sum of the kinetic and potential energy of all the molecules in an object

heat

thermal energy that flows from something at a higher temperature to something at a lower temperature

conduction

transfer of thermal energy through direct contact (like ironing)

convection

transfer of energy in a fluid (gas or liquid) by movement of the the heated particles

radiation

transfer of energy through electromagnetic waves (like sunlight)

heat insulator

a material that doesn't allow heat to flow through it easily

electric charge

is a property that allows an object to exert an electric force on a object without touching it.

electrical conductor

a material that allows electrons to move easily through it

electrical insulator

a material that doesn't allow electrons to move easily through it

circuit

a closed, conducting path

electric current

the flow of charges through a wire or any conductor

series circuit

the current has only one loop to flow through like a string of Christmas lights

parallel circuit

contain two or more branches for current to move through like our houses do

sound

a type of wave that is produced by a vibrating object and that travel travels through matter

medium

matter that waves travel through

transverse wave

the medium moves back and forth at right angles to the direction the wave travels

compressional (longitudinal) wave

the medium moves back and forth in the same direction the wave travels like sound waves

refraction

a bending of waves as it moves from one to another / occurs when speed of wave changes.

wavelength

the distance between one point on a wave and the nearest point just like it (measured from compression to compression or rarefraction to rarefraction.

crest

the distance between any two troughs or crest.

(transverse wave)

trough

the lowest point of a transverse wave

frequency

the number of waves that pass each second

amplitude

related to energy of wave /distance from rest position to crest or trough on transverse wave

reflection

when a wave strikes an object and bounces off it

diffraction

a bending of waves around a barrier

hertz

used to measure frequency

what are electromagnetic waves

radio waves,microwaves,infrared,visible light,UV,x-rays,and gamma rays

radio waves

low frequency electromagnetic waves with long wavelengths

x-rays

high frequency electromagnetic waves with short wavelengths

visible light

the range of electromagnetic waves that we can detect with our eyes

solids

particles packed together tightly and constantly vibrating in place

liquid

particles move more freely past each other but aren't free to move far apart

gases

particles are far apart/ no definite shape or volume

plasma

matter containing positive and negative charged particles at very high temperatures (as in the stars)

element

all the atoms of a substance is alike

pure substance

either an element or a compound

compound

a substance in which the atoms of two or more elements are combined in a fixed proportion

heterogeneous mixture

a mixture in which the different materials can be distinguished easily

homogenous mixture

a mixture in which two or more substances are blended evenly throughout

solution

a homogeneous mixture that will never settle/ the particles are so small they can't be detected by a microscope

physical property

characteristics that you can observe without changing the identity like color, shape, size, melting point, etc.

physical change

a change in size, shape, or state of matter

chemical property

characteristic of a substance that indicates it can undergo a chemical change (like ability to burn)

chemical change

a change of one substance to another like burning, rusting, or corroding

conservation of mass

mass is neither created nor destroyed/ same before and after reaction

nucleus

center of atom containing protons and neutrons

atom

smallest piece of matter that still retains the property of the element

protons

positively charged nuclear particles

neutrons

nuclear particles with no charge

electrons

negatively atomic particles that orbit the nucleus

mass number

sum of protons and neutrons

atomic number

the number of protons

number of neutrons

mass number - atomic number

periodic table

elements arranged by increasing atomic number

chemical formula

tells what elements a compound contains and the exact number of atoms like H20

chemical bond

a force that holds atoms together in a compound

metals

conduct electricity, ductile, malleable, shiny (on left of periodic table)

metalloid

semi-condcuctors like silicon (transition elements)

non-metals

usually gases, do not conduct electricity very well (on right of periodic table)

net force

a combination of all forces acting upon an object

open circuit

doesn't allow charge to flow through

closed circuit

allows charge to flow through

Doppler effect

change in perceived pitch that occurs hear the sound moving.

concave

is curved inward

convex

is curved outward

distance/time

speed(meters/second→m/s)

distance/speed

time (seconds)

speed x time

distance (meters)