Question

A bullet moving with 10 m/s hits a wooden plank. The bullet stops after penetrating the plank 2 cm deep. Calculate the retardation of the bullet.

Answer 1

Step 1, Given data

Initial velocity = 10 m/s

Distance = 2 cm =0.02 m

Final velocity = 0

Step 2, Finding the retardation

From the equation of motion

$v^2=u^2+2as$

Putting all the values

$0=10\times 10+2\times a\times 0.02$

After solving

a = -2500 m/$s^2$

Hence the retardation is 2500 m/$s^2$