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# Gensci reviewer 3 rd qrtr k 12

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### Gensci reviewer 3 rd qrtr k 12

1. 1. GENERAL SCIENCE REVIEWER THIRD QUARTER 2012-2013MOTION WAVES • Before you will be able to describe the • a periodic disturbance that moves away motion of an object, you must first be from a source and carries energy with it able to tell exactly where it is • A vibration causes wave motion. When positioned. Describing exact position you observe a wave, the source is entails two ideas: describing how far always a vibration. the object is from the point of PARTS OF A WAVE referenceand describing its direction Crest- highest point relative to that point of reference. Trough- lowest pointPOINT OF REFERENCE Wave length- distance between 2 waves (trough • Something to refer to: something to to trough/ crest to crest) which somebody can refer in order to Wave height- distance from crest to trough check direction, as a guide or as an aid Amplitude- range from normal position of wave to communication. to either side • The object or point from which movement is determined. • Movement is relative to an object that appears stationary.DISTANCE • the total length of the path travelled by the object • the length of the entire path that the object travelledDISPLACEMENT FREQUENCY • the distance between the initial position • is the number of waves that pass a and final position of the object particular point every one second • the shortest distance between the PERIOD object’s two positions, like the distance • the time required for one complete wave between its point of origin and its point to pass a given point of destination, no matter what path it SPEED/VELOCITY took to get to that destination • V = wavelength x frequencySPEED LONGITUDINAL WAVES • Speed is the distance traveled in a given • occur when the individual particles of amount of time. amedium vibrate back and forth in the • Scalar quantity direction in which thewaves travel • Speed= Distance TRANSVERSE WAVESTime • occur when the individual particles or • 100 km/h segments of a medium vibrate from sideVELOCITY to side perpendicular tothe direction in • Speed with direction which the waves travel • Vector quantity • Velocity = DisplacementTime • 100 km/h North EastACCELERATION • the rate at which the velocity of a body changes with time • a = V final – V initial Time • If an object does not change its position at a given time interval,then it is at rest or its speed is zero or not accelerating. • If an object covers equal distance at MECHANICAL WAVES equal intervals of time, then itis • require a medium for wave propagation moving at constant speed and still not • (medium: rope, coil spring, air, water) accelerating. ELECTROMAGNETIC WAVES • If an object covers varying distances at • requireno material medium for their equal intervals of time, thenit is passage. Thus, they can pass through moving with changing speed or empty space. velocity. It means that theobject is • (gamma waves, UV waves, radio waves) accelerating.
2. 2. SOUND WAVES otherforms or transferred to other • longitudinal and mechanical waves objects orplaces. • travels the fastest in solidthan in liquid • Object which has greater mass has and in air greater heat energy. • V = 331 + (temperature in air) x 0.6 HEAT TRANSFER • Reflection = echo • related to change in temperature orLIGHT WAVES change in the relative hotness or • Light travels in straight lines coldness of an object. • Light travels much faster than sound HEAT TRANSFERS IN THREE WAYS: • We see things because they reflect light • Conduction- higher temperature to into our eyes lower temperature (spoon gets hot when • Shadows are formed when light is put in a hot soup) blocked by an object • Convection- cool air sinks, warm air • 300, 000, 000 m/s speed of light rises • travels the fastest in the vacuum • Radiation- particles travel through aCOLOR vacuum • Light is the combination of all (seven) colors. ELECTRICITY • Light can be separated using a prism in • a type of activity arising from the a process called dispersion. existence of charge • RED, BLUE and GREEN (primary • The basic unit of charge is that on the colors) proton or electron. • The protons charge is called positiveCOLOR COMBINATION while the electrons is negative. • A particle of matter usually has a charge. • The charge is positive or negative. • Two particles with the same charges, both positive or both negative, repel or drive away each other, while two particles with unlike charges are attracted. CONDUCTORS • allow electricity to flow through themRGB (RED GREEN BLUE) easily. Copper wire is a good example and makes up our housing and applianceBlue + Green = CyanBlue + Red = Magenta wiringRed + Green = Yellow INSULATORS • materials that dont allow electricity toBlue + Green + Red = White pass through them easily. Materials suchCMYK (CYAN, MAGENTA, YELLOW, KEY/BLACK) as rubber are good insulators and areCyan + Magenta= Blue used around appliance and house wires to keep the electricity from creating aCyan + Yellow = GreenYellow + Magenta = Red short circuit THE LAW OF CONSERVATION OF CHARGECyan + Magenta+ Yellow = Black • Charges cannot be created nor destroyed, but can betransferred fromHEAT WAVES one material to another.The total charge • a form of energy that refers to the in a system must remain constant. thermal energy that is ‘in transit’ or in ELECTROSTATIC LAW the process of being transferred. • Like charges repel and unlike charges • It stops to become heat when the attract. transfer stops. • After the energy is transferred, say to -mct another object, it may again become thermal energy or may be transformed to other forms. • Any object issaid to possess thermal energy due to the movement of its STUDY HARD!!! particles. How isheat related to thermal energy? GOOD LUCK!!! • Like any other forms of energy, thermalenergy can be transformed into