Bowing vs. Plucking the Strings
In order to play a violin, you must use a bow instead of plucking the strings with your fingers. The bow is made of horsehair, which is very rough. To produce sound, the bow is drawn across the strings of the violin, and the horsehair exerts frictional forces on the strings. Horsehair is used on the bow because it exerts a static frictional force instead of a sliding force.
When the hairs of the bow rub across a string, they grab the string and push it forward with static friction. The string's restoring forces will eventually overpower the static friction, and the string suddenly starts sliding backward across the hairs. Since the hairs exert little sliding friction, the string will complete half of a vibrational cycle. But, as it stops to reverse the direction, the hairs grab the string again and push it forward. This process repeats over and over to produce the unique sound made by bowing the strings of a violin.
Plucking the string of the violin does not utilize a frictional force. Instead, the string quickly vibrates in and out of its equilibrium position until its kinetic energy is lost to the environment. Translated into how we hear it, the plucked string creates a quick initial pitch which then gradually decays. The bowed string creates a longer lasting pitch because of the repeated process of frictional displacement followed by a restoring force.
When the hairs of the bow rub across a string, they grab the string and push it forward with static friction. The string's restoring forces will eventually overpower the static friction, and the string suddenly starts sliding backward across the hairs. Since the hairs exert little sliding friction, the string will complete half of a vibrational cycle. But, as it stops to reverse the direction, the hairs grab the string again and push it forward. This process repeats over and over to produce the unique sound made by bowing the strings of a violin.
Plucking the string of the violin does not utilize a frictional force. Instead, the string quickly vibrates in and out of its equilibrium position until its kinetic energy is lost to the environment. Translated into how we hear it, the plucked string creates a quick initial pitch which then gradually decays. The bowed string creates a longer lasting pitch because of the repeated process of frictional displacement followed by a restoring force.
