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 to the second child.

Answer 1

speed of sound in air = 346m/s

speed of sound in aluminium rod = 6420m/s

let the length of the rod be x

we know,

time = distance/speed

time taken in air = x/346

time taken in aluminium rod = x/6420

ratio =(x/346)/(x/6420)

= x/346 * 6420/x    [reciprocal]

x would get cancelled

= 6420/346

after cancelling

= 18.55

          

Answer 2

speed of sound in air = 346m/s

speed of sound in aluminium rod = 6420m/s

let the length of the rod be x

we know,

time = distance/speed

time taken in air = x/346

time taken in aluminium rod = x/6420

ratio =(x/346)/(x/6420)

= x/346 * 6420/x [reciprocal]

x would get cancelled

= 6420/346

after cancelling

= 18.55