Grades 6–8 · Arts & Music
How can a violin bow keep a string vibrating?
A plucked string receives a brief input of energy and then gradually loses it. A moving violin bow can keep adding energy, allowing a note to continue through much of a stroke. The contact between bow hair and string is central to that difference.
In the diagramBowing repeatedly grips and releases the string1. Stick: move together2. Slip: string returnsBowStringBow energy → string → bridge and body → airMany stick-slip cycles fit inside one bow stroke.Rosin supports repeated grip and release.Enlarged motion; suitable bowing is assumed.
Rosin on the hair helps produce a cycle of sticking and slipping. During the sticking part, the string at the contact point moves with the bow. The displaced string is under tension, and waves travel along it and reflect at its ends. Under suitable bowing conditions, the returning motion helps the string break free and slide back past the hair. It can then catch again, beginning another cycle.
These rapid cycles happen many times while the bow travels steadily in one direction. They are not the slower back-and-forth strokes of the player’s arm. At a supplied rate of 440 cycles each second, one cycle lasts about 2.27 milliseconds. A half-second stroke contains 220 such cycles.
The bridge transfers vibration to the violin body, which interacts with surrounding air. The drawing greatly enlarges the sideways string motion so that the two contact roles are visible. It assumes suitable bowing rather than calculating the force or position needed for a particular tone.
About this explanation
Starting knowledge: Understand friction, vibration, frequency and time per cycle.
Sources
- Yamaha — The Structure of the Bow
- University of New South Wales, Music Acoustics — Bows and Strings