December 14 2015 What type of wave is

December 14, 2015 What type of wave is a sound wave? What is included in one wave cycle?

Learning Targets 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.

Q: What is a wave? Disturbance (vibration) that travels through a medium (substance)

Q: What is a wave? 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

Q: What is a wave? 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!

Q: What is 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

Q: What are some types of 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.

Q: What are some types of waves? Longitudinal ◦ Particles move parallel to the direction of energy transfer Particles move left and right, energy transferred left and right.

Q: What are some types of waves? Electromagnetic Waves ◦ Can transfer energy in a vacuum (SPACE!) ◦ Ex: Light waves Mechanical Waves ◦ Cannot transfer energy in a vacuum ◦ Ex: sound

Q: What are some parts of waves? Transverse ◦ Crest (High point) ◦ Trough (Low point)

Q: What are some parts of waves? Longitudinal ◦ Compression (High pressure) ◦ Rarefaction (Low pressure)

Q: What are some parts of waves? 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

Q: What are some parts of waves? Units: same as those for DISTANCE ◦ Meters ◦ Usually with a prefix NANO 1 m = 109 nm

Q: What are some parts of waves? 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

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

Q: What do you mean when you talk about the frequency and period of a wave? Frequency ◦ Amount of wave cycles that pass in a certain amount of time f = cycles time ◦ NOT the same as speed of a wave!

Q: What do you mean when you talk about the frequency and period of a wave? Frequency, cont ◦ Units: Hertz, Hz (cycles per second) ◦ Increased frequency means higher “pitch”

Q: What do you mean when you talk about the frequency and period of a wave? Period ◦ The amount of time it takes for one complete cycle (wavelength) ◦ Units: same as for time (seconds, hours, minutes, years, etc)

Q: What do you mean when you talk about the frequency and period of a wave? Relationship between the two ◦ As you increase the frequency, the period will decrease ◦ Inversely related

Q: What do you mean when you talk about the frequency and period of a wave? ◦ Equation: ◦ Period = 1/frequancy ◦ Units: Frequency is hertz (Hz) Period/time in seconds

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

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

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

PRACTICE PROBLEMS 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 ______.

Q: What is the relationship between speed, frequency, and wavelength? 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!

Q: What is the relationship between speed, frequency, and wavelength? As the wavelength increases: ◦ Waves spread out, so frequency decreases ◦ Wavelength and frequency are INVERSELY related

Q: What is the relationship between speed, frequency, and wavelength? 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

PRACTICE PROBLEMS 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.

PRACTICE PROBLEMS 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.

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