Question

A bullet hits a wall with a velocity of 20m/s and penetrates it up to a distance of 5 cm. Find the deceleration of the bullet in the wall.

Answer 1

Step 1, Given data

Initial velocity of the bullet u = 20 m/s,

Final velocity v = 0,

distance traveled, S = 5 cm = 0.05 m

Step 2, Finding the negative acceleration

From the 3rd equation of motion,

$v^2-u^2=2aS$

Putting all the values

0 - (20)² = 2 × 0.05 × a

Or, 0.1 a = - 400

Therefore, a = $\frac{-400}{0.1}$ = - 4000 m/s²

Therefore, deceleration of the bullet in the wall = - 4000 m/s².