Question

A bullet initially moving with a velocity 20 $m{s}^{-1}$ strikes a target and comes to rest after penetrating a distance of 10 cm in the target. Calculate the retardation caused by the target.

Answer 1

Step 1, Given data

Initial velocity u = 20 m/s

Final velocity v = 0
Distance traveled s = 10 cm = 0.1 m

Step 2, Finding the acceleration

Let acceleration be ‘a’.

Using the third equation of motion,

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

Now putting all the values

$0^2={20}^2+2\times a\times 0.1$

After solving

$a=-2000$ m/$s^2$

Hence retardation caused by the target is 2000 m/$s^2$