Question:
A bullet going with speed $350 \mathrm{~m} / \mathrm{s}$ enters a concrete wall and penetrates a distance $5.0 \mathrm{~cm}$ before coming to rest. Find the deceleration.
Solution:
$\mathrm{u}=350 \mathrm{~m} / \mathrm{s} ; \mathrm{v}=0 ; \mathrm{s}=5 \times 10^{-2} \mathrm{~m}$
$\mathrm{v}^{2}=2^{2}+2 \mathrm{as}$
$0^{2}=(350)^{2}+2(\mathrm{a})(0.05)$
$\mathrm{a}=-12.25 \times 10^{5} \mathrm{~m} / \mathrm{s}^{2}$