 What type of wave is a sound wave?  What is included in one wave cycle?

 You will be able to identify the parts and properties of a wave.  Compare and contrast longitudinal and transverse waves.  Calculate the values associated with waves.

Disturbance (vibration) that travels through a medium (substance)

 When a wave isn’t traveling, it is considered to be in equilibrium position ◦ Imagine a stretched out slinky just sitting on a desk- that’s equilibrium

Once a particle moves at the front, the energy of that particle will travel throughout the slinky to the other end. That creates a wave!

 Waves transfer energy, not particles ◦ This explains why boats sitting in the middle of the ocean can just sit in one spot, and don’t travel with waves

Transverse o Particles move perpendicular to the direction of energy transfer  Particles move up and down, but energy is transferred left to right.  These are the waves we draw/imagine when we hear the word.

 Longitudinal ◦ Particles move parallel to the direction of energy transfer  Particles move left and right, energy transferred left and right.

 Electromagnetic Waves ◦ Can transfer energy in a vacuum (SPACE!) ◦ Ex: Light waves  Mechanical Waves ◦ Cannot transfer energy in a vacuum ◦ Ex: sound

 Transverse ◦ Crest (High point) ◦ Trough (Low point)

 Longitudinal ◦ Compression (High pressure) ◦ Rarefaction (Low pressure)

 Wavelength: length of one cycle ◦ Transverse: 1 trough and 1 crest ◦ Longitudinal: 1 compression and 1 rarefaction ◦ Ex.  Distance from one crest to the next  Distance from one trough to the next  Distance from one compression to the next

 Units: same as those for DISTANCE ◦ Meters ◦ Usually with a prefix NANO  1 m = 10 9 nm

 Amplitude ◦ Displacement (movement) of particles from equilibrium (rest) position ◦ Most of the time considered to be from rest to crest or rest to trough ◦ Harder to measure in longitudinal waves

 Amplitude, cont ◦ Units: Same as DISTANCE (some form of meters, usually with prefix- see wavelength section) ◦ Increased amplitude means louder/more intense sound.

 Frequency ◦ Amount of wave cycles that pass in a certain amount of time ◦ NOT the same as speed of a wave! f = cyclestime

 Frequency, cont ◦ Units: Hertz, Hz (cycles per second) ◦ Increased frequency means higher “pitch”pitch

 Period ◦ The amount of time it takes for one complete cycle (wavelength) ◦ Units: same as for time (seconds, hours, minutes, years, etc)

Relationship between the two ◦ As you increase the frequency, the period will decrease ◦ Inversely related

◦ Equation: ◦ Period = 1/frequancy ◦ Units:  Frequency is hertz (Hz)  Period/time in seconds

1. Frieda the fly flaps its wings back and forth 121 times each second. The period of the wing flapping is ____.

2. The period of the sound wave produced by a 440 Hertz tuning fork is _________.

3. A tennis coach paces back and forth along the sideline 10 times in 2 minutes. The frequency of her pacing is ______.

4. Olive Udadi accompanies her father to the park for an afternoon of fun. While there, she hops on the swing and begins a motion characterized by a complete back-and-forth cycle every 2 sec. The frequency of swing is _____. The period of swing is ______.

 Speed is not dependent on wavelength or frequency ◦ Speed IS dependent on the medium of travel ◦ Sound waves travel fastest through solids and slowest through gases  Think of the closeness of particles/ease of energy transfer!

 As the wavelength increases: ◦ Waves spread out, so frequency decreases ◦ Wavelength and frequency are INVERSELY related

 WAVE Equation:  Speed = wavelength x frequency  Units: ◦ frequency in hertz (Hz) ◦ wavelength can be any type of distance units ◦ velocity is in distance units over seconds

1. Mac and Tosh stand 8 meters apart and demonstrate the motion of a transverse wave on a snakey. The wave can be described as having a vertical distance of 32 cm from a trough to a crest, a frequency of 2.4 Hz, and a horizontal distance of 48 cm from a crest to the nearest trough. Determine the amplitude, period, and wavelength and speed of such a wave.

2. Ocean waves are observed to travel along the water surface during a developing storm. A Coast Guard weather station observes that there is a vertical distance from high point to low point of 4.6 meters and a horizontal distance of 8.6 meters between adjacent crests. The waves splash into the station once every 6.2 seconds. Determine the frequency and the speed of these waves.

 Part 1-3  Test on Friday  Quizlet Review will be up by Thursday Morning at latest