Question

Two children are at the opposite end of an iron pipe. One struks the end of the pipe with a stone. Calculate the ratio of the time taken by sound waves in air and in iron to reach the other child. Use speed of sound in (i) air $=344m{s}^{-1}$ and (ii) iron $=5130m{s}^{-1}$.

Answer 1

Let the length of the pipe be $L$.
Speed of sound in air $v_a=344m/s$
So time taken by sound wave in air $t_a=\frac{L}{v_a}=\frac{L}{344}$
Speed of sound in iron $v_i=5130m/s$
So time taken by sound wave in iron $t_i=\frac{L}{v_i}=\frac{L}{5130}$
Thus ratio of both times $\frac{t_a}{t_i}=\frac{5130}{344}=15$