1. Simple Harmonic Motion and Waves

2. What is common between the following?
Acrobat swinging on a trapeze
Child swinging on a swing
Pendulum of a grandfather clock
A wrecking ball swinging back and forth.

3. SIMPLE HARMONIC MOTION
The back and forth vibrating motion (often called oscillatory motion) of an object. A graph of this motion is a sine curve.

4. SIMPLE HARMONIC MOTION OF A MASS ATTACHED TO A SPRING

5. SPRING SIMPLE HARMONIC MOTION ANIMATION

6. What is a wave? Mechanical and Electromagnetic A wave
is a wiggle in space and time
is caused by a vibration
carries energy not matter
Hawaii resident man who surfed what is now known to be the world’s largest wave -- a 78-foot monster. Reed notified the Hawaii bureau and new News Editor Oskar Garcia chased down the surfer, who’d ridden the wave in in Portugal in November and managed to stay out of the limelight for several months until the Guinness World Records certified the wave as the biggest ever.
Mechanical and Electromagnetic

7. 1st Major Category Mechanical Waves
waves that require a medium (solid, liquid, or gas) through which to travel.
Speed of the waves depends on the elasticity of the medium
Are governed by Newton’s Laws
3 types of mechanical waves: transverse, longitudinal, and surface

8. Types of mechanical waves
Transverse wave- particle displacement is perpendicular to the wave motion
Examples include waves in piano and guitar strings

9. Types of mechanical waves (cont)
Longitudinal waves- particle displacement is parallel to the wave motion
Sound is a longitudinal wave
Fluids, liquids, gases, and plasmas usually only transmit longitudinal waves

10. Types of mechanical waves (cont)
Surface waves- a combination of both transverse and longitudinal waves
Waves on the water’s surface are examples of surface waves

11. Properties of mechanical waves*
1. Crest- the high point of a wave
2. Trough- the low point of a wave
3. Amplitude- measurement of the amount of energy the wave carries
*Some properties are only found in transverse waves and some properties are only found in longitudinal waves.

12. Properties of mechanical waves* (cont)
4. Wavelength- the distance between the midpoint of one crest/trough to the midpoint of the next crest/trough
Compression – In longitudinal waves, sections of shorter wavelength
Rarefaction – In longitudinal waves, sections of longer wavelength
5. Line of equilibrium- the resting point of a wave

13. Concept Check: Label the crest, trough, wavelength, amplitude, and line of equilibrium on the transverse wave.

14. Check your answer!

15. Concept Check: On the given longitudinal wave, label the compression, rarefaction, and wavelength.

16. Check your answer!

17. Velocity of mechanical waves
Calculated using the formula
V = fλ
Where v is velocity, f is frequency, and λ is wavelength.

18. Period and Frequency of Waves
Period (T) is amount of time for one cycle
T = 1/f
Frequency (f) is how many waves pass in one second.
f = 1/T
Relationship between these variables is inverse….
As frequency of waves increases the period of a single wave decreases.

19. Solve the following problem
Problem: Calculate the velocity of waves in water that are 0.4 m apart and have a frequency of 2 Hz.
Answer: v = fλ
v = (2 Hz)(0.4 m)
v = 0.8 m/s

20. Again….
Problem: What is the wavelength of a 340 Hz sound if the velocity of sound is 343 m/s?
Answer: v = fλ
343 m/s = (340 Hz)λ
1.0 m = λ

21. A Little More Practice
A speaker vibrates at a frequency of 200 Hz. What is its period?
T = 1/f /200Hz = .005 sec
What does .005 sec mean in words?
A swing has a period of 10 seconds. What is its frequency?
F = 1/T /10sec = .1 Hz

22. Wave Interference
Waves have a very unique property, they can occupy the same space at the same time.
This phenomenon is called interference!
Interference can be either constructive or destructive.

23. Wave Interference (Cont)
Constructive interference, or reinforcement, occurs when the crests of two waves overlap each other and the amplitudes are added together.

24. Wave Interference (cont)
Destructive interference, or cancellation, occurs when a crest and a trough of two waves overlap and their amplitudes cancel out.

25. can be classified into two categories
Waves
transfer or carry
do not move or carry
can be classified into two categories
mechanical waves
are further classified into
are a special type of
include examples such as
transfer energy through
include examples such as
do not require
transverse waves
move
move
includes
to transfer

26. Simple Harmonic Motion and Waves
Part 2

27. Day One Review What are the two types of waves?
Waves must move either parallel or ________________ to the movement of energy.
The point of the wave that is furthest away from the resting line is the __________________.
The ______________________ measures the amount of energy in the wave.

28. 2nd Major Category Electromagnetic waves
Wave does not need a medium to travel
Wave that is partly electric and partly magnetic
All EM waves are located on the electromagnetic spectrum
All EM waves travel at the speed of light (3.0 x 108 m/s)

29. The Electromagnetic Spectrum

30. Solving an EM problem
The velocity for all EM waves is 3.0 x 108 m/s and is represented by the letter c.
Therefore, the equation
v =fλ
becomes
c = fλ!

31. Solving an EM problem (cont)
Problem: The wavelength of yellow light is 556 nm. What is the frequency?
Answer: c = fλ
3.0 x 108 m/s = f(556 nm)
5.4 x 1014 Hz