Lectures on Physics has been derived from Benjamin Crowell's Light and Matter series of free introductory textbooks on physics. See the editorial for more information....

Changing the axis

An object's angular momentum can be different depending on the axis about which it rotates. Figure g shows shows two double-exposure photographs a viola player tipping the bow in order to cross from one string to another. Much more angular momentum is required when playing near the bow's handle, called the frog, as in the panel on the right; not only are most of the atoms in the bow are at greater distances, r , from the axis of rotation, but the ones in the tip also have more momentum, p. It is difficult for the player to quickly transfer a large angular momentum into the bow, and then transfer it back out just as quickly. (In the language of section 5.4, large torques are required.) This is one of the reasons that string players tend to stay near the middle of the bow as much as possible.

Last Update: 2009-06-21