Mechanical wave motion terms

medium - the substance through which a mechanical wave travels.

rest position - the natural orientation of the medium without the effects of a wave disturbance. For example, a pond may be perfectly flat and still. This is its rest position and it will return to this position after a wave completes its disturbance.

wave pulse - a single disturbance through a medium.

wave - a series of wave pulses at regular intervals of time.

transverse wave - a wave in which the medium is displaced perpendicular to the direction of travel of the wave itself. A surface water wave would be an example. This type of wave is described in appearance by its crests (high points) and troughs (low points). High and low are simply relative to the rest position.

longitudinal (compressional) wave - a wave in which the medium is displaced parallel to the direction of travel of the wave itself. An accordion being played would be an example. This type of wave is described in appearance by its compressions (high density of medium) and rarefactions (low density of medium).

For the following crest and trough can be substituted with compression and rarefaction.

wavelength (l) - the distance between two consecutive crests or troughs, or any other similar points on a wave.

frequency (f) - the number of waves passing a fixed point in a given time. Usually written as waves per second or Hertz (Hz). The inverse of the period.

period (t) - the time required for one complete wave (crest to crest) to pass a fixed point. The inverse of the frequency.

wave speed (v) - (a) Distance traveled by a wave in a given time. (b) Wavelength divided by the period. (c) Wavelength multiplied by the frequency.

amplitude (A) - how much the medium is displaced by a wave. The distance from the rest position to the crest or the trough.

standing wave - wave pattern that occurs due to the reflection of waves in a medium with distinct and "fixed" ends.

To determine the wavelength of the standing waves you observe in a slinky you will need the following info about the slinky and the wave:

stretched length of the slinky -  L
number of crests observed in slinky - n
The equation for the wavelength is:
l  =  2L/n

## Wave Question/Prediction/Conclusion Sheet

 QUESTION PREDICTION CONCLUSION 1. Determine the relationship between frequencies of three standing waves: 1 segment, 2 segments, 3 segments. f f 2. Determine the relationship between frequency and amplitude. f f 3. Determine the relationship between frequency and wavelength. f f 4. Determine the relationship between frequency and wave speed. f f 5. How can you increase the speed of a wave pulse in the slinky? f f 6. What factor(s) change the amplitude of a wave pulse in the slinky? f f 7. Determine the relationship between frequency and period. f f