Physical Science Vocabulary

 

Forces and Motion

acceleration - the rate at which velocity changes with time

average speed - total distance traveled divided by time

conservation of energy- energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes

energy - the property of a system tht enables it to do work

mechanical equilibrium- the state of an object or a system of objects for which any imposed forces can cancel out and no acceleration occurs

force - any influence that can cause an object to be accelerated

friction - the resistive force that opposes the motion or attempted motion of an object past another with which it is in contact, or through a fluid

mass - the quantity of matter in an object

mechanical energy - a form of energy due either to the position of the object or the motion of the object

momentum - the product of the mass of an object and its velocity

Newton's 1st law of motion- an object at constant velocity remains at that velocity unless a net force acts upon it; an object at rest remains at rest unless a net force acts upon it

Newton's 2nd law of motion - force varies with mass and rate of change in speed, force equals mass times acceleration

Newton's 3rd law of motion - for every action there is an equal and oppostie reaction

potential energy - the energy something has because of its position

power - the time rate of work; how long it takes to do work

speed - distance traveled by time

velocity - the speed of an object and specification of its direction of motion

velocity vector - an arrow drawn to scale representing the magnitude and direction of a force/velocity

work - the product of the force and the distance through which the force moves

weight - the gravitational force exerted on an object by the nearest most-massive body

Light and Sound

amplitude- for a wave or vibration, the maximum displacement on either side of the equilibrium

concave lens - curved like the inner surface of a sphere

convex lens - curved like th eouter surface of a sphere

focal length - the distance from the center of the mirror to the focal point

focal point - a point on the optical axis where light rays converge

frequency- the number of times an action occurs in a given time

hertz- the unit of frequency, one of these equals one vibration per second

longitudinal wave - a wave in which the medium vibrates in a direction parallel to the direction in which the wave travels

mirror- a surface capable of reflecting sufficient undiffused light to form an image of an object placed in front of it

period- the time required for a vibration or a wave to make a complete cycle

pitch- the property of sound that makes it high or low

reflection- the return of light rays from a surface in such a way that the angle at which a given ray is returned is equal to the angle at which it strides the surface

refraction- the bending of a wave as it passes either through a non-uniform medium or from one medium to another, caused by differences in wave speed

sound wave - a longitudinal vibratory distrubance that travels in a medium and can be heard by the human ear when in the approximate frequency range 20-20,000 hertz

tone- a sound of distinct pitch and duration

transparent- the term applied to materials through which light can pass in straight lines

transverse wave - a wave in which the medium vibrates in a dirction perpendicular to the dirction in which the wave travels

wave- a disturbance or vibration propagated from point to point in a medium or in space

wave speed- the speed with which waves pass a particular point; frequency times wavelength

wavelength- the distance between successive crests, troughs, or identical parts of a wave

Atomic Structure

actinides - the inner transition metals of the seventh period

alkali metals - the most reactive group of all the metals; reactivity increases as you go down the group; very reactive with water so must be stored unter oil

alkaline earth metals- reactive group of metals that make very useful compounds

covalent bond - a chemical bond in which atoms are held together by their mutual attraction for two electrons they share

decomposition - one substance breaking down into two or more substances

diatomic molecule - two atoms of the same element bonded together

double displacement - one atom changes places with another of like charge

group - a vertical column in the periodic table

halogens - salt formers: a very active group of elements that exist in nature as diatomic molecules

inner transition metals- two subgroups-lanthanides and actinides-of the transition metals

ionic bond - the electrical force of attraction that holds ions of opposite charge together

lanthanides - in inner transition metals of the sixth period

noble gases - a very unreactive group of elements; the only group composed of all nonmetals

nonmetals - these elements tend to be dull, brittle, not ductile or malleable, do not conduct heat or electricity very well, good insulators

period - a horizontal row in the periodic table

shell - a region of space about the atomic nucleus within which an electron may reside

single displacement - one atom replace another of like charge

synthesis - two or more substances combining to from one substance

transition elements- ten groups of metal elements; generally are less reactive and form colorful compounds

valence electrons - the outer energy level electrons

Electricity

alternating current - electrically charged particles tht repeatedly reverse direction, vibrating about relatively fixed positions

ampere - the unit of electric current

anode - positive electrode

battery - a devise tht converts chemical energy into electric energy

cathode - negative electrode

closed circuit - a complete path, from the source of electrons, through a conductor and back to the source of electrons

conductor - substance that permits the flow of electricity

coulomb - the charge on 6,240,000,000,000,000,000 electrons

Coulombs Law- for any two electrically charged bodies, the relationship among the electric force the bodies exert on each other, the charge on the two bodies, and the distance between them

diode - electronic component through which electric current can flow in one direction only

direct current - electrically charged particles flowing in one direction only

electric current - The flow of electric charge that transports energy from one place to another

electrode - metal plate through which electric current enters or leaves an electrolysis cell, battery or vacuum tube

electrolyte - a liquid or solution that conducts an electric current

insulator - substance that does not conduct electricity

Ohm's law - the current in a circuit varies in direct proportion to the voltage across the circuit and inversely with the circuit's resistance

open current - an incomplete path which does not allow the flow of electrons

parallel circuit - a conductor with two or more paths for the electrons

series circuit- a conductor with only one path for the electrons

volt - the unit of electric potential