Question

Question 8
Two children are at opposite ends of an aluminium rod. One strikes the end of the rod with a stone. Find the ratio of times taken by the sound wave in air and in aluminium to reach the second child.

Answer 1

Velocity of sound in air = 346 m/s
Velocity of sound wave in aluminum = 6420 m/s
Let length of rode be 1m.
Time taken for sound wave in air, $t_1=\frac{1}{Velocityinair}$
Time taken for sound wave in aluminum, $t_2=\frac{1}{Velocityinaluminum}$
Therefore, $\frac{t_1}{t_2}=\frac{velocityinaluminium}{velocityinair}=\frac{6420}{346}=18.55:1$