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A construction worker's helmet slip and ...

A construction worker's helmet slip and falls when he is 78.4 m above the ground .He hear the sound of the helmet heating the ground 4.23 second after it slipped Find the speed of sound .(g=9.8 m `s^(2)`)

Text Solution

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Here,h =78.4 =m, g=9.8 `ms^(-2)` ,u=0?
`h=ut+(1)/(2)gt ^(2)`
`therefore 78.4 =0xxt+(1)/(2)xx9.8xxt^(2)`
`therefore t^(2)=(78.4xx2)/(9.8)=16 therefore t=4s`
The time take by the helmet to reach the ground=4s So the time taken by the sound to reach the height 78.4 m = (4.23-4)s speed of sound=`("distance")/("time")=(78.4)/(0.23)~~340.87 ms^(-1)`
The speed of sound in air is 340.87 `ms^(-1)`
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