question_answer

\[\frac{{{\partial }^{2}}u}{\partial {{t}^{2}}}={{c}^{2}}\frac{{{\partial }^{2}}u}{\partial {{t}^{2}}}\] represents the equation for:

A) Vibration of a stretched string

B) Motion of a projectile in a gravitational field

C) Heat flow in thin rod

D) Oscillation of a simple pendulum