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A worker's helmet slips and falls when h...

A worker's helmet slips and falls when he is 78.4 m above the ground. He hears the sound of the helmet hitting the ground 4.23 seconds after it slipped. Find the speed of sound in air.

Text Solution

Verified by Experts

Acceleration of the helmet, `g=9.8 m s^(-2)`
Distance covered by the helmet, d= 78.4 m
Time of motion of helmet, `t_(1)` = ?
Velocity of sound, v= ?
Time taken by sound travel a distance d, `t_2 = 4.23 - t_(1)`
We have, for motion of helmet
`d= 1/2 gt_(1)^2`
`t_(1)= 4 s`
For propagation of sound
`d= vt_2`
`78.4 = v(4.23 - t_(1))`
`v = 340.8 m s^(-1)`
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