Q. A bullet of mass $0.05\ kg$ moving with a speed of $80\ ms^{- 1}$ enters a wooden block and is stopped after a distance of $0.40\ m$. The average resistive force exerted by the block on the bullet is
A) $300\ N$
B) $20\ N$
C) $400\ N$
D) $40\ N$
Explanation
(c) Work done by stopping force = loss in $KE$
$F \times 0.40 = \frac{1}{2} \times 0.05 \times (80)^{2} \Rightarrow F = 400\ N$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.