Waves

Chapter 12.3

Wave motion

A wave is the motion of a disturbance

Simple harmonic motion produces waves!!

Wave mediums

• Mechanical wave – a wave that requires a medium (solid, liquid, or gas) to move through– Ex: Sound waves are mechanical because they

require air, liquid or solid to move though (sound can not travel in outer space)

• Non-mechanical wave – does not require a medium to move– Ex: light waves travel through the vacuum of outer

space where there is no medium (all EM waves)

Wave Types

• Pulse wave – one wave that travels alone (a)• Periodic wave – a wave that moves up and down

repeatedly (b)

Transverse Waves• Transverse wave – a wave whose particles vibrate

perpendicularly to the direction of the wave motion

Parts of a wave• Crest – highest point above equilibrium

• Trough – lowest point below equilibrium

• Wavelength – distance between two adjacent similar points of a wave

Longitudinal Wave

• Longitudinal wave - a wave whose particles vibrate parallel to the direction of the wave motion.

Period is inverse to frequency• Period – amount of time for one complete vibration• Frequency – number of complete cycles per second.

Calculating speed of a wave

v = fλv- speed of wave (m/s)f – frequency of wave (Hz)λ – wavelength (m)This can be used with both mechanical waves

and non-mechanical waves.

Practice Problems

• Pg 335 1-7• 1a = 343 m/s, b =2.29 ms, c=0.787 m• 2a = 343 m/s, b=457 Hz, c=2.19 ms• 3 = at lower freq bc wavelength is inversely related

to freq• 4= 1.50 m/s• 5 = 3.00 m• 6 = 0.600 m/s• 7 = 8.00 m/s