Figure 2.
Dispersion of substrate-borne waves in a rush stem. (a) Relation between the square root of the frequency f (kHz) and velocity c (m s−1) for five stems: velocity first increases with the square root of frequency and then remains stationary whatever the frequency. The vertical dashed line is at f=5 kHz (i.e. √f=2.23 kHz). (b) Non-dimensionalized analysis investigating the combined effects of frequency and stem radius on wave velocity. Observations are compared with Bernouilli–Euler (dashed line) and Timoshenko (continuous line) beam theories.