Do Some Physics Before Shooting!

Jim, the scientist, is planning to do a dangerous stunt in which he puts his life at stake. He asks his assistant to shoot him while he stands behind a stack of identical books.

Before he does the stunt, he test fires a bullet on a single book and confirms that the bullet fired at speed \(\SI[per-mode=symbol]{457.2}{\meter\per\second}\) penetrates the \(\SI[per-mode=symbol]{3.5}{\centi\meter}\) thick book and comes out from the other side at speed \(\SI[per-mode=symbol]{400}{\meter\per\second}\).

What is the minimum number of books Jim needs to stack up so that he can pull off this stunt safely?

Details and Assumptions:

  • Air resistance is neglected.
  • The deceleration of the bullet within the books is constant.

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