1. Vibrations and Waves

2. What are Vibrations?
Vibrations are back and forth movements exhibited about a resting position.

3. Examples of Motion due to Vibrations and Damping
A Simple Pendulum: Comprises mainly of a long string that is attached to a mass
2. A spring 3.
Damping:

4. Simple Harmonic Motion
A vibratory motion that is regular and repeating is called a simple harmonic motion or simply a periodic motion.
SHM produce sine curves
Example: the motion of a simple pendulum, pendulums in grandfather’s clocks.

5. What are Waves?
Waves: are disturbances across a medium that transfer energy.
Waves do not transfer matter.
Waves can be caused due to vibrations

6. Description of a Wave
A wave can be defined by the following parameters:
Crests: The high positions on a wave are called crests
Troughs: The low positions on a curve are called troughs.
Amplitude: is the distance from the midpoint to the crest (or trough) of a wave.
Wavelength: Is the distance between successive identical parts of the wave.

7. Description of a Wave (cont..)
Frequency: How often a vibration occurs in a given period of time.
Example: A pendulum swinging back and forth in one second is said to have completed 1 cycle in 1 second.
Units of Frequency are hertz.
The time period of a wave is the time it takes to complete one vibrational cycle.
Relationship between frequency and time period:

8. Wave Speed
Wave speed: can be described how fast a certain point in the wave is travelling.
Wave speeds depend on the medium in which the wave is travelling.
Wave Speed Formula:

9. Major kinds of waves
Longitudinal Waves: When particles move along the direction of the wave rather than at right angles to it.
Example:
Transverse Waves: Whenever the motion of the medium is at right angles to the direction in which a wave travels, the wave is a transverse wave.

10. Interference
Interference: a phenomenon in which waves interact with each other.
Constructive interference: When crests overlap with crests or troughs overlap with troughs.
Deconstructive interference: When a crest overlaps with a trough and vice versa.

11. Interference (cont..)

12. Standing Waves
Standing Waves: are a result of interference where two waves of the same amplitude and wavelength pass each other in opposite directions.
Points of destructive interference are created and these points are known as nodes.
Points of maximum amplitude created on a standing wave is called antinode.

13. Standing Waves (Cont..)

14. The Doppler Effect
The Doppler Effect: Is a phenomenon in which there is an apparent change in the frequency due to the motion of the source of sound or the receiver.