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

TransverseoParticles 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 = 109 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 = f = cyclescyclestimetime

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