Question

The average force necessary to stop a bullet of mass 20 g moving with a speed of 250 m/s, as it penetrates into the wood for a distance of 12 cm is

• A. $2.2 \times 10^{3}N$
• B. $3.2 \times 10^{3}N$
• C. $4.2 \times 10^{3}N$
• D. $5.2 \times 10^{3}N$

Answer 1

Answer: (D)

$5.2 \times 10^{3}N$

Answer 2

$u = 250m/s$, $v = 0$, $s = 0.12metre$

$F = ma = m\left( \frac{u^{2} - v^{2}}{2s} \right) = \frac{20 \times 10^{- 3} \times (250)^{2}}{2 \times 0.12}$

$\therefore$ $F = 5.2 \times 10^{3}N$