Question

A lead bullet of mass 2 Kg, traveling with a velocity of 20 $m/s$, comes to rest after penetrating 20m in a still target. Find the resistive force applied by the target and acceleration of the bullet.

• A. Acceleration = 20 m/s² and F = -40 N
• B. Acceleration = 40 m/s² and F = +80 N
• C. Acceleration = 40 m/s² and F = -80 N
• D. Acceleration and force are 0

Answer 1

The correct option is C

Acceleration = 40 m/s² and F = -80 N

We know that, $v^2$​ = $u^2+2as$​

v = 0 $m/s$

u = 20 $m/s$, s = 20 m
So, $0={20}^2+2\times a\times 20$

Acceleration = $-10m/s^2$

So, $F=ma=2\times -10$

F = - 20N