Download - Chapter 1: Waves
Chapter 1: WavesWaves interact and transfer energy in predictable ways
1.1 Waves transfer energy•How forces cause waves•How waves transfer energy•How waves are classified
wavea disturbance that transfers energy from one place to another
waves transfer energy over distance without moving matter the entire distance
Where Do Waves Get Energy?
Vibration-Any movement that follows the same path repeatedly. An object that is vibrating is moving. A force causes the vibration.
An object that is moving has energy.A vibrating object gives off some of its
energy to nearby particles. This movement of energy from a vibrating source outward is a wave.
Waves get their energy from a vibration.
VibrationsExample: The top of a drum vibrates
after it is struck by a drum stick. It moves up and down several times creating sound.
Example: Your ear drum vibrates in response to sound which enables you to hear.
mediumany substance that a wave moves through
ex. water, the ground, a rope, air
Waves Through Matter and SpaceMedium-Matter or substance
through which a wave is transmitted.Water is a medium for ocean waves.Air is a medium for sound waves.All phases of matter solids, fluids,
plasmas, can act as a medium.
mechanical wavesany wave that transfers energy through matter (must have matter to work)
wavelength
transverse wavesthe direction in which the wave travels is perpendicular to the direction of the disturbance
longitudinal wavethe wave travels in the same direction as the disturbance
1.2 Waves have measurable properties•how amplitude, wavelength and frequency are measured•how to find a wave’s speed
Amplitudethe distance between a line through the middle of a wave and a crest or trough.
see p. 17
wavelengththe distance from crest to crestor trough to trough
frequencythe number of wavelengths passing a fixed point in a certain amount of time (usually a second)
Waves / second (hertz)
Wave speedspeed = wavelength x frequencyS = λ ∙ f
5 QQDraw a transverse wave.Label the wavelength.Label the amplitude.Draw a low amplitude transverse wave and a high frequency transverse wave.
Draw a longitudinal wave, label the rarefactions.
Name Amplitude Wavelength Frequency WaveSpeed
1.3 Waves behave in predictable ways•How waves change as they encounter a barrier•What happens when waves enter a new medium•How waves interact with other waves
reflectionthe bouncing back of a wave after it strikes a barrier
refractionthe bending of a wave as it enters a new medium
occurs because waves travel at different speeds in different mediums
diffractionthe spreading out of waves through an opening or around an obstacle
interferencewaves interact with other wavesthey can add energy to, or take energy away from each other
the meeting and combining of waves
Suppose that you create a wave by moving a rope up and down. What will happen if you increase the energy you put into the rope? What will happen if you increase the speed of the motion?amplitude, frequency, wavelength
wavelengthfrequencyamplitudereflectionrefractiondiffractionmediumdisturbanceforcehertzmechanical wavewave
transverse wavelongitudinal waveinterferencecresttroughvibrationconstructive
interferencedestructive
interferencewave speedcompressionrarefactionwaves / second