# 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 - Science

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.

#### Solution

Let the length of the aluminium rod be d.

Speed of sound wave in aluminium at 25°C, vAl = 6420 ms-1

Therefore, time taken by the sound wave to reach the other end,

t_(Al)=d/"v"_(Al)=d/6420

Speed of sound wave in air at 25°C, vAir = 346 ms-1

Therefore, time taken by sound wave to reach the other end,

t_(Air)=d/"v"_(Air)=d/346

The ratio of time taken by the sound wave in air and aluminium:-

t_(Air)/t_(Al)=(d/346)/(d/6420)=6420/346=18.55

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#### APPEARS IN

NCERT Class 9 Science Textbook
Chapter 12 Sound
Q 8 | Page 174