## Properties of a Wave-

• Amplitude-the maximum extent of a vibration or oscillation, measured from the position of equilibrium.
• Wavelength-the distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave.
• Period- A Time period is the time needed for one complete cycle of vibration to pass a given point. As the frequency of a wave increases, the time period of the wave decreases.
• Frequency-the number of crests of a wave that move past a given point in a given unit of time. The most common unit of frequency is the hertz (Hz), corresponding to one crest per second.

### Simple Harmonic Motion

• Simple harmonic motion-oscillatory motion under a retarding force proportional to the amount of displacement from an equilibrium position.
• If a spring is sprung and is attached to a wall it will not stop moving back and forth if no other force is acted upon it.
• This constant back and for the motion is simple harmonic motion

### Tacoma Bridge and Resonance

• Resonance- the reinforcement or prolongation of sound by reflection from a surface or by the synchronous vibration of a neighboring object.
• Tacoma Bridge was a bridge that fell shortly after is was built due to the resonance of the wind.
• It fell because the wind matchee the bridges resonant frequency and the contestant resonance caused it to collapse