2-2 Speed of Sound

A man strikes a long steel rod at one end. Another man, at the other end with his ear close to the rod, hears the sound of the blow twice (once through air and once through the steel rod), with a time interval between the two sounds Dt = 0.1 s. What is the length L of the steel rod? For steel, the bulk modulus is B = 2.1x1011 Pa, and the density r = 7.0 x 103 kg/m3. Take the speed of sound in air vair = 340 m/s.

Example 1