Gordon E. Jones

Ballistics calculations of R. W. Gurney

Gurney’s method of calculating speed imparted to driven metal by high explosives is described and applied to several geometrical configurations. The method permits derivation of a differential equation with a closed‐form solution describing the acceleration of the metal. Because of its versatility, Gurney’s approach continues to find new applications. This article serves as an appendix to a recent article on Gurney and, in addition, provides instructive applications of classical mechanics.

Easy displacement versus time graphs for a vibrating string: Tuning a guitar by television

When a vertical, vibrating string is silhouetted against a television screen, a wavelike shape may be seen. The shape will appear distinct and stationary if the ratio of the string’s fundamental frequency to 60 Hz is the ratio of small integers. The vertical scan of the (horizontally sweeping) electron beam is responsible for this shape, which amounts to a displacement versus time graph for the string. The effect can be used to tune stringed musical instruments to absolute pitch.