Amplitude, Period, and Frequency

Simple harmonic motion repeats itself or is periodic. This means that it can be described using amplitude, period, and frequency.

Amplitude

Definition: The amplitude is the distance from the midline, or the maximum displacement from a state of equilibrium.
  • Represented with A and measured in meters
  • Can be used to describe the range of motion
  • Found by averaging the extremes; the (Max + Min) / 2

Period

Definition: The time period it takes for an object to complete one revolution.

            • Represented with T and measured in seconds
            • Can be easily found by comparing similar adjacent extrema, like one maximum to the next.
            • Devices like clocks have very predictable periods

Frequency

Definition: The number of revolutions per second

  • Represented in Hertz
  • Depends on the period; shorter period means high frequency
  • Since clocks have predictable periods, they consequentially have predictable frequencies
  • f = 1/T, so frequency and period are inverses

One example of a pendulum:


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