An 80.0-m-long brass rod is struck at one end. A person at the other end hears two sounds as a result of two longitudinal waves, one traveling in the metal rod and the other traveling in the air. What is the time interval between the two sounds? (The speed of sound in air is 344 m/s; relevant information about brass can he found in Table 11.1 and Table 12.1.)

Solution 11E Introduction First we have to calculate the speed of sound at brass from the information given in the table 11.1 and table 12.1. Then we can calculate the speed difference and from the speed difference we can calculate the time difference. Step 1 First we have to calculate the speed of longitudinal sound wave passing through brass. The speed of longitudinal wave is given by B vb= Where B is the bulk modulus and is the density. Now from the given table we have B = 6.0 × 1010Pa And = 8.6 × 10 Kg/m 3 Hence the speed is given by 6.0×10Pa 3 vb= 8.6×10 Kg/m= 2.641 × 10 m/s