Conceptual Physics 1999 Hewitt Bloom High School

Definitions Vibration- a wiggle in time Atoms Wave- a wiggle in space and time Earthquakes, water, sound, etc.

25.1 Vibration of a Pendulum Period, T (s)- time required for one complete cycle Back and forth Two pendulums of the same length have the same period, regardless of mass Longer pendulum string- longer T Shorter string, shorter T

25.2 Wave Description Simple Harmonic Motion (SHM)- back-and-forth motion vibratory motion Sine curve- shape traced out when a pendulum is followed P. 373 Figure 25.2 Physics Physlets P.16.9 (Animation 3) Wave on a String Phet Frequency, f (Hertz, Hz)- number of cycles per second Inverse relationship to period (T) f=1/T and T=1/f

Sine Waves Crest- top-most portion of a wave Trough- bottom-most portion of a wave Amplitude (A)- vertical distance measured from equilibrium to a crest Wavelength ( )- horizontal distance from crest-to-crest or trough-to-trough

25.3 Wave Motion Energy transfer with a medium Energy is transferred by a disturbance in the medium, not the particles in the medium moving Sound- compression of air molecules in waves Earthquake- compression of Earth or rise-and-fall of Earth Energy can be transferred without a medium Light- oscillation of electromagnetic energy As well as X-rays, infrared, microwaves, FM, AM, etc.

25.4 Wave Speed Regardless of medium, wavelength and frequency are needed Speed = distance ÷ time Speed = wavelength ÷ period = wavelength frequency v = /T = f Speed of sound in air ranges from m/s Temperature dependant

25.5 Transverse Waves Transverse waves- motion of the medium moves perpendicularly to the direction the energy travels Ropes, surface water waves, stringed instruments Electromagnetic waves Physics Physlets I.17.1 (Animation 1 & 2)

25.6 Longitudinal Waves Longitudinal waves- motion of the medium moves parallel to the direction the energy travels Slinky pulled back Physics Physets I.17.1 (Animation 3)

25.6 Interference Interference pattern- waves from two separate sources overlapping Constructive interference- the crest of one wave overlaps with the crest of another wave In Phase- Increases amplitude Physics Physlet I.17.3 (Animation 1) Destructive interference- the crest of one wave overlaps with the trough of another wave Out of Phase- Decreases amplitude Physics Phslets I.17.3 (Animation 2)

Interference Pattern

25.8 Standing Waves Standing waves- when the incident and reflected waves overlap Nodes- the portion of the waves that remain stationary Antinodes- the portion of the waves that have the largest disturbance wave4.html wave4.html

25.9 Doppler Effect Doppler Shift- change in frequency due to motion between the sound source and receiver Physics Physlet I.18.4 (Animation 4) Motion only depends on the objects getting closer or further away. It doesn’t matter who does which. Blue Shift Source stationary, receiver moving towards source Receiver stationary, source moving towards receiver Red Shift Source stationary, receiver moving away from source Receiver stationary, source moving away from receiver

Doppler Shift (Sound & Light)

25.10 Bow Waves Bow waves- Constructive interference in water as created by an object moving faster than the waters’ speed 2D wave

25.11 Shock Waves Shock waves- Constructive interference in air as created by an object moving faster than the speed of sound 3D wave Sonic Boom- increased amplitude of so many waves arriving at our ears all at one time Physics Physlet I.18.4 (Animation 5)

Terms (lots of ‘em) Amplitude Antinodes Blue shift Bow wave Constructive interference Crest Destructive interference Doppler effect Frequency Hertz In phase Interference pattern Longitudinal wave Node Out of phase Period Red shift Shock wave Simple harmonic motion Sine curve Sonic boom Standing wave Transverse wave Trough Vibration Wave Wavelength