Question

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

V_air = 346 m s⁻¹ (at 25°C)

V_AI = 6420 m s⁻¹ (at 25°C)

Let the length of the pipe = lm.

Time taken by sound to travel from one child to another through air (t₁) = `"Distance"/"Speed"`

t₁ = `"l"/346 "s"`           ...(i)

Similarly, the time taken by sound to travel from one child to another through aluminium:

t₂ = `"l"/6420 "s"`        ...(ii)

Equation From (i) and (ii)

`t_1/t_2` = `1/346 ÷ 1/6420`

= `"l"/346 xx 6420/"l"`

= `6420/346`

= `18.55/1`

`t_1 : t_2` = `18.55 : 1`