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.

Explanation

To find the ratio of the times taken by the sound wave in air and in aluminum to reach the second child, we can follow these steps:

### Step 1: Define the Variables
Let:
- \( d \) = length of the aluminum rod (distance between the two children)
- \( v_{air} \) = speed of sound in air = 346 m/s
- \( v_{aluminum} \) = speed of sound in aluminum = 6420 m/s

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