A rifel loses 1/20 of its velocity in passing through a planks. what is the least number of planks required to stop the bullet
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hello friend...!!
to find the least number planks required ,
⇒let us consider , the thickness of the plank be S m
⇒the initial velocity be V m/s
⇒ let the final velocity be 19V / 20 m/s
⇒ according t the formula we can write ,
( 19V / 20 )² - v² = 2as
let us consider the number of plank required is equal to ' n ' .
so therefore ,
0 - v² = 2nas
⇒ n = v ² / ( 19/20)² - v²
⇒ n = v ² / (361v² - 400v²) / 400
⇒ n = 10.25
let us consider approximately n ≈ 11
therefore the number of plank required is equal to 11 .
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hope it is useful..!!
to find the least number planks required ,
⇒let us consider , the thickness of the plank be S m
⇒the initial velocity be V m/s
⇒ let the final velocity be 19V / 20 m/s
⇒ according t the formula we can write ,
( 19V / 20 )² - v² = 2as
let us consider the number of plank required is equal to ' n ' .
so therefore ,
0 - v² = 2nas
⇒ n = v ² / ( 19/20)² - v²
⇒ n = v ² / (361v² - 400v²) / 400
⇒ n = 10.25
let us consider approximately n ≈ 11
therefore the number of plank required is equal to 11 .
--------------------------------------------------
hope it is useful..!!
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