← all cardsTopic 11 · Wave Motion · Definitions
Wave speed, v
● VERBATIM — examined word-for-wordThe speed at which the wave profile (energy) travels in the direction of propagation. A constant for a given wave in a given medium — NOT the particle velocity.
v = fλWhat this actually means
v is how fast the shape travels, not how fast any particle moves. The crest you watched a moment ago is now downstream; v tracks that crest.
For a given medium, v is fixed. Turn the frequency up and the wavelength shrinks so that fλ still equals the medium's speed.
Never apply v = fλ to a particle. Particle speed varies through every cycle (it is SHM); wave speed never does.
Prove it — watch it be true
- Set v with the slider and watch the ghost profile advance steadily
- Compare with any single bead: it speeds up and slows down every cycle
- Two different speeds live on one wave — the constant one is v