Q: A bullet of mass ‘m’ moving with velocity ‘v’ stops in a wooden block after penetrating through a distance x. If ‘f’ is the resistance offered by the block to the bullet then the stopping distance in terms of momentum (P) and f is
(a) $ \displaystyle \frac{P}{m f} $
(b) $ \displaystyle \frac{P^2}{m f} $
(c) $ \displaystyle \frac{P^2}{2 m f} $
(d) $ \displaystyle \frac{P}{2 m f} $
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Ans: (c)
Sol: $ \displaystyle \frac{1}{2}mv^2 = f x$
$ \displaystyle \frac{P^2}{2m} = f x $