Kinky physics
An exaggerated view of the transverse displacements of a bowed violin string, illustrating the "slipstick" mechanism that generates a Helmholtz wave with a single kink travelling along the string. (a) The shape of a string at five equally spaced time intervals, when the kink is on the far side of the bow from the bridge. This is known as the "sticking regime". At the position where the string is being bowed, the string moves with the same speed, and in the same direction, as the bow. (b) The shape of the string at five equally spaced time intervals for the "slipping regime", when the kink is travelling between the bow and the bridge, and back. The string now moves in the opposite direction to the bow. (c) The displacement of the string at the bowing point. (d) The force Tsinq exerted by the strings on the bridge as function of time, where T is the tension of the string.