1. Properties of Mechanical Waves
Frequency, Period, Wavelength, Amplitude and
Wave Speed (yes another formula!)

2. Period
The period of a pendulum is the time it takes to move through one cycle
This is from when the string is pulled to one side, let go and the ball moves to the opposite side and then returns to the starting place

3. Frequency Frequency is the number of complete cycles in a given time
For a wave, the frequency is the number of wave cycles that pass a point in a given time
Frequency is measured in cycles per second or hertz (Hz)
A wave’s frequency equals the frequency of the vibrating source producing the wave

4. Equations for frequency and period
T = 1/f or f = 1/T
In the above equations: T stands for the period in time (seconds) and f stands for frequency in hertz
If given the period of an object you can calculate the frequency
Also if given the frequency of an object you can calculate the period

5. Wavelength
Wavelength is the distance between a point on one wave and the same point on the next cycle of the wave
For a transverse wave, wavelength is measured between crests or troughs
For longitudinal waves, the wavelength is measured between compressions or rarefractions

6. Wave Speed Vw = ƒ λ Vw = wave velocity (speed) ƒ = frequency
λ = wavelength
Wavelength is in meters (m)
Frequency is in hertz (Hz)
Wave velocity (speed) is in meters/second (m/s)

7. Wave Speed Example
One end of a rope is vibrated to produce a wave with a wavelength of 0.25 meters. The frequency of the wave is 3.0 hertz. What is the velocity of the wave?
Vw = ƒ λ
Wavelength (λ ) = 0.25 meters
Frequency (ƒ) = 3.0Hz
Vw= 0.25 meters x 3.0 Hz = 0.75m/s

8. Wave Speed cont.
The speed of a wave can change if it enters a new medium or if pressure or temperature change
Most of the time, wave speed is constant
If a wave is moving at a constant speed then the wavelength is inversely proportional to frequency
waves with a lower frequency have a longer wavelength
Waves with a higher frequency have shorter wavelengths

9. Amplitude
The amplitude of a wave is the maximum displacement of the medium from its rest position
The more energy a wave has, the greater its amplitude