A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

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A

acceleration
the rate of increase in velocity with respect to time; a change in speed and/or direction

accuracy
how close your [experimental] value is to the accepted value

air resistance
resistance or friction on objects moving through air

Alpha radiation (Alpha decay)
a helium nucleus (an element containing two protons and two neutrons) is released; causes ionization but because it is so big it looses its energy very quickly; the skin of humans can stop Alpha radiation from harming good cells in the body; occurs when the strong force is no longer able to hold a big nucleus together resulting in an electromagnetic repulsion of an Alpha particle

amplitude
strength; magnitude

anode
the positive terminal for most elements; is the negative terminal of the battery, the electrode through which electrons are removed from the electrolyte medium internal to the battery; oxidation reaction occurs at the electrode

B

battery simple (electrochemical cell)
contains two electrodes (anode and cathode) of dissimilar metals immersed in a medium that conducts charge

Beta radiation (Beta decay/emission)
occurs when a neutron in the nucleus is converted into a proton and an electron and then the electron is ejected; emits particles in order to stabilize the atom

Big Bang Theory
the theory that states that the universe was created from a single point that contained all matter and energy of the entire universe and exploded to create the universe

black hole
a large mass that has been condensed into a very little space generating a large force of gravity drawing light and mass towards it, supposed to once have been a star; since light captured by the mass is completely absorbed by the mass, the mass is black - thus giving it the name black hole

British units
units of measurement used that are not metric
examples: feet, horsepower, feet/second, pound, second

C

cathode
the negative terminal for most elements; is the positive terminal of the battery, the electrode through which electrons enter the electrolyte medium internal to the battery; reduction reaction occurs at the electrode

center of gravity
the average location of all of the mass in an object; the point about which an object will rotate; the point that follows a parabolic path when flying through the air; the point at which an object will balance

centrifugal force
the feeling of being pulled outward as you move in a circle (because of inertia); this is not a true force

centripetal acceleration
the acceleration that acts inward toward the center of the circle; centripetal acceleration = velocity²/radius

centripetal force
the inward acting force allowing an object to exhibit circular motion

current
the flow of charge through an element

D

DC
direct current; current whose amplitude is constant with time

displacement
is the change in position from one point in space to another; the total straight line distance traveled; a vector quantity
example: If a person travels 40 meters around a circle and ends up where he/she started, the displacement is 0.

distance
the total amount of space traveled; a scalar quantity
example: If a person travels 40 meters around a circle and ends up where he/she started, the distance covered is 40 meters.

E

elastic collision
collisions where no energy is lost to heat, sound, or deformity; collision where kinetic energy is conserved; collisions when objects do not stick together and no energy is lost to the environment

electrolyte***
a nonmetallic electric conductor in which current is carried by the movement of ions *** Merriam-Webster's Medical Dictionary; Merriam-Webster, Inc., 2002 (www.dictionary.com)

electromagnetic force
An attractive and repelling force that acts over an infinite distance; force between charges and/or current; force generated by a time varying electric and magnetic field in an electromagnetic wave; is 10³⁶ times stronger than gravity; gives objects strength, shape, ability to bend, and ability to hold objects

electromagnetic radiation
the electric and magnetic fields of a wave generated by a source but able to exist there after without the source frequencies greater than zero
examples: light, radio waves, microwaves, x-rays

electromagnetic spectrum
spectrum of electrical and magnetic fields in the frequency range greater than zero
examples: light, radio waves, microwaves, x-rays

electron
a negatively charged point particle with a mass equal to 9.11 x 10^-31 kg; electrons exist about the nucleus of an atom; electrons can exist in free space

energy
ability to do work; there are different types of energy
example: some different types of energy include potential, kinetic, nuclear, electrical, solar, chemical, heat, and hydroelectrical energy

English units
units of measurement used that are not metric
examples: feet, horsepower, feet/second, pound, second

equilibrium

F

force
a push or a pull; the rate of increase of momentum; force = mass x acceleration

friction
the force of a surface against the motion of an object rubbing against it

• static friction
  the friction between objects at rest
• kinetic friction
  the friction between objects in motion

(the four) fundamental forces
gravity, electromagnetic force, weak nuclear force, strong nuclear force

G

gamma ray *
an electromagnetic wave of very high frequency given off in the reactions of nuclei or nuclear particles; a high-energy photon. Gamma rays are like X rays, but have a shorter wavelength. Gamma rays are emitted when a nucleus in an excited state changes to a more stable state. *Barnhart, Robert K. The American Heritage Dictionary of Science. (p 245) Boston: Houghton Mifflin Company, 1986.

gravitons
theoretical particles that have no mass; particles that are exchanged with everything creating gravitational bonds

gravity
the attractive fundamental force that attracts masses together; gravity acts over infinite distance but is the weakest of the four fundamental forces

H

Hertz (Hz)
cycles per second; a measurement of frequency

horsepower
an English measurement of power; 1 horsepower = 746 Watts

hypothesis
an educated guess; a brief description of what one will do for an experiment

I

impulse
an instantaneous change in momentum

inelastic collision
when energy is lost to another form (sound, heat, or deformity) and/or objects stick together; collisions where energy is not conserved

inertia
the resistance of an object to a change in motion

ions
positively or negatively charged atoms

(Sir) Isaac Newton ** (1642-1727)
English mathematician and scientist who invented differential calculus and formulated the theory of universal gravitation, a theory about the nature of light, and three laws of motion. His treatise on gravitation, presented in Principia Mathematica (1687), was supposedly inspired by the sight of a falling apple. **The American Heritage® Dictionary of the English Language. 4th ed. : Houghton Mifflin Company, 2000. (www.dictionary.com)

J

Joules (J)
a measurement of energy and work

K

Kepler's first law
A planet follows an elliptical orbit having the sun at one focus.

Kepler's second law
A line joining any planet to the sun sweeps out equal areas in equal times.

Kepler's third law
The square of the period of any planet about the sun is proportional to the cube of the planet's mean distance from the sun.

kilogram (kg)
MKS (metric) standard unit of mass; 1000 grams

kinetic energy
the energy due to the motion of an object; kinetic energy = 0.5(mass)(velocity²)

kinetic friction
the friction between objects in motion

L

law of the conservation of energy
energy cannot be created or destroyed; it can only be transferred from one form to another

law of the conservation of momentum
in a closed system, the momentum of the system must remain the same

lever arm
distance from the force to the axis of rotation

light
the part of the electromagnetic spectrum that is visible to the human eye

linear speed
distance traveled per unit of time

M

magnetic fields
a philosophical field generated by the motion of charge

magnetism
attraction between North and South poles

mass
a measure of matter in an object; the nonrelativistic ratio of the net force applied to the object and its acceleration

matter
anything in the form of a liquid, gas, solid, or plasma with mass

meter (m)
the standard metric unit of length

metric units
universal unit of measurement, much more common than the English system of measurement in many places
examples: Newtons, meters, kilograms, Joules, watts, seconds

momentum
a measure of the motion of a body equal to the product of mass and velocity; momentum = mass x velocity

N

negative work
when an object decreases in energy
example: friction, air resistance

net force
the total force resulting from all the forces on an object

neutron
a component of an atom's nucleus that has about the same mass as the proton but no charge; helps glue the nucleus together with the strong force

Newton, Sir Isaac ** (1642-1727)
English mathematician and scientist who invented differential calculus and formulated the theory of universal gravitation, a theory about the nature of light, and three laws of motion. His treatise on gravitation, presented in Principia Mathematica (1687), was supposedly inspired by the sight of a falling apple. **The American Heritage® Dictionary of the English Language. 4th ed. : Houghton Mifflin Company, 2000. (www.dictionary.com)

Newton's first law
An object at rest will stay at rest and an object in motion will maintain that motion in a straight line until acted upon by an outside force.

Newton's second law
The sum of all forces acting on an object causes a mass to have an acceleration; the acceleration is always in the same direction as the net force.

Newton's third law
If object A exerts force on object B, then B must exert a force of the same magnitude in the opposite direction.

Newtons (N)
a measurement of force (kg m/s²)

normal force
a force acting perpendicular to a surface

nuclear chain reaction
the occurrence of an atom that has a nucleus too big to be held together by the strong force breaks down emitting particles and components in order to reach a stable equilibrium

nucleus
the center of an atom consisting of protons and neutrons

nuclei
plural of nucleus

O

oscillation
the repeated nature of a pattern; the path of a swinging pendulum when bases are neglected -- pendulum swings from A to B and back to A (a periodic change in kinetic and potential energy results over time)
example: the periodic change in the state of a phenomenon with respect to time

oxidation
any reaction in which electrons are lost

P

Pascals (Pa)
a measurement of pressure; 1 Pa = 1N/meter squared (N is for the unit of Newtons)

percent error
a measure of how accurate your experimental value is to the accepted value; | (actual - experimental)/actual | x 100 = % error

period
the time it takes for a periodic phenomenon (such as the swinging of a pendulum) to repeat its nature

photons
elementary particles of light that have no mass and have the ability to behave as waves; packets of radiant energy

plasma
a quasi-neutral gas of electrons, ions, and neutrons (nearly the same number of positive and negative charge) that can be manipulated with electric and magnetic fields

positive work
when objects increase in energy

positron *
an elementary particle having the same magnitude of mass and charge as an electron, but exhibiting a positive charge, present in cosmic rays and also emitted in beta decay; a positive electron *Barnhart, Robert K. The American Heritage Dictionary of Science. (p. 515) Boston: Houghton Mifflin Company, 1986.

potential difference
the force or energy supplied (or required) to push charge through an element

potential energy
the energy stored inside an object; the amount of energy it takes to move an object from one point in space to a second point in space in the presence of a force field; in the electrical engineering field, it is the amount of energy expended to move an object from one point in space to another point in space in the presence of an electrostatic field; potential energy = (mass)(gravity)(height)

power
the rate at which work is done; the rate of increase in energy with respect to time

precision
how close all of your data is to each other

pressure
the amount of force over a certain amount of area (force/area)

propulsion
to propel; to shoot

protons
positively charged components of an atom's nucleus

Q

quarks
smaller particles that make up the components of an atom

R

radioactivity
when the nucleus of an atom is unstable and gives off particles or energy in form of electromagnetic radiation

reduction
any reaction in which electrons are gained

resultant vector
the total sum of all vectors

revolution
when an object spins around an external axis exhibiting a periodic motion

rotation
when an object spins around its internal axis

rotational speed
the number of revolutions or rotations per unit of time

S

scalar
a quantity only described by its magnitude (number)
examples: distance, speed

second (s)
standard unit of time

significant figures (significant digits)
the necessary number of figures in a number; the number of figures is based exclusively on the measuring tool used to collect data; it is based on measuring to the smallest division plus one guess
example: Assume a ruler measures a length of string between 9.2 cm and 9.3 cm, then you would write the number as 9.25 cm.

simple machines
pulley, inlined plane, lever, wheel and axle, screw, wedge

slope
change in y-axis over change in x-axis; rise over run; slope = (y2 -y1)/(x2 -x1)

speed of light (c)
~3 x 10⁸m/s

stable equilibrium
when one perturbs a system away from equilibrium and over time the system approaches the same equilibrium

static friction
the friction between objects at rest

strong force (strong nuclear force)
the strongest force of the four fundamental forces; acts only over the size of a nucleus as an attractive force

T

tension
the force along a string, rope, chain, etc. tending to force the ends in opposite directions

torque
a twisting force; the product of a force and perpendicular lever arm length

U

unstable equilibrium
when a system is perturbed away from equilibrium and over time does not return to the original equilibrium

V

vector
a quantity described by both magnitude and direction; horizontal and vertical vectors are independent of each other
example: displacement, velocity

velocity
the motion of an object in a particular direction; displacement divided by time; a vector quantity

visible light spectrum
the range of the electromagnetic spectrum visible to the human eye

W

Watts
a measurement of power; Joules/second

wave
a disturbance or state of motion that periodically changes as it moves from one point in space to another

weak force (weak nuclear force)
the force involved in radioactivity

weight
a force due to gravity; mass times gravity

work

X

X rays *
an electromagnetic ray having an extremely short wavelength that ranges from about 0.1 to 10 nanometers, formed by the bombardment of a metal target with high-speed electrons in a vacuum tube or by the transfer of electrons to the inner shells of heavy atoms. *Barnhart, Robert K. The American Heritage Dictionary of Science. (p. 730) Boston: Houghton Mifflin Company, 1986.

Y

Z

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References:
*Barnhart, Robert K. The American Heritage Dictionary of Science. Boston: Houghton Mifflin Company, 1986.

**The American Heritage® Dictionary of the English Language. 4th ed. : Houghton Mifflin Company, 2000. (www.dictionary.com)

*** Merriam-Webster's Medical Dictionary; Merriam-Webster, Inc., 2002
(www.dictionary.com)