Waves Simple Harmonic Motion The back and forth

Waves

Simple Harmonic Motion • The back and forth or periodic motion of an object • Ex. Pendulum, swings, second hand of a clock

Waves • Disturbance that moves through space or through a medium (material) • Transfer energy not matter from one place to another

In which direction will segment x move as the wave passes through? • (1) down, only (2) up, only (3) down, then up, then down (4) up, then down, then up

Importance of Waves • There are two ways to transmit information/energy in our universe: particle motion or wave motion • Waves can be produced two ways: – Mechanical Waves- vibration of particles • Sound, water waves (water drop) – Electromagnetic Waves- changing strength in an electromagnetic field (no medium required) • Light, ultraviolet, x-rays (EM wave)

• Pulse- single disturbance • Wave train-series of evenly timed disturbances

Transverse Waves • Motion of the medium is at right angles (perpendicular) to the direction which the wave travels • Ex. Vibrating string of musical instrument, electromagnetic waves( radio waves, light waves)

Longitudinal Waves • Particles vibrate parallel to the direction of wave travel and energy source • Ex. Sound

Longitudinal Wave terms • Compression- (similar to crests) – particles close together (high density) • Rarefactions (similar to troughs)- particles spread out or rarefied (low density)

Wave Property Definition Symbol Unit Determined by: Amplitude Maximum distance from the rest position A m Source of wave; amount of energy being carried

Velocity Wave Property Velocity Definition Symbol Speed of the wave; distance wave travels in a unit of time v Unit m/s Determined by: The medium

Frequency Wave Property Frequency Definition • # of vibrations that pass a point each second • Cycles per second Symbol Unit Affected by- f Hz Determined by source not medium! Ex. 10 cycles pass a fixed point in a wave train in 5 seconds. What is the frequency of the wave?

Period Wave Property Definition Symbol Unit Affected by- Period Time it takes for one complete vibration T s Determined by source of vibration not medium Which wave has the longest period?

Wavelength Wave Property Definition Symbol Unit Affected by- Wavelength Distance wave moves during one complete vibration λ m Velocity Frequency (Determined by medium)

Wave Equation • Wave speed = frequency x wavelength • Ex. What is the speed of a wave with a frequency of 10 Hz and a wavelength of 0. 25 m? • 2. 5 m/s

Frequency and Period • Frequency = cycles/sec • Period = sec/cycle