Popsicle-Stick Cobra Wave
The cobra wave is a popular physical phenomenon arising from the explosion of a metastable grillage
made of popsicle sticks. The sticks are expelled from the mesh by releasing the elastic energy stored during
the weaving of the structure. Here we analyze both experimentally and theoretically the propagation of the
wave front depending on the properties of the sticks and the pattern of the mesh. We show that its velocity
and its shape are directly related to the recoil imparted to the structure by the expelled sticks. Finally, we
show that the cobra wave can only exist for a narrow range of parameters constrained by gravity and rupture
of the sticks.