A bullet loses 10% of its speed after passing through a wooden plank.How many such planks should be placed one after the another so that bullet does not come out?

Dear neeru

let the thickness of one block is t

(9v/10)² = v² - 2at

.81v² = v² - 2at

2at = .19v².........................1

let n block is used

0 = v² - 2a(nt)

n = v² /2at

  = v² /.19v²

  = 100/19

  = 5.26

so 6 block is used

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