Question

A bullet initially moving with a velocity 20 m/s strikes a target and comes to rest after penetrating a distance 10 cm into the target. Calculate the retardation caused by the target.

Answer 1

Initial velocity u = 20 m/s

Final velocity v = 0

Distance travelled s = 10 cm = 0.1 m

Let acceleration be 'a'.

Using the third equation of motion,

v² − u² = 2as

We get,

(0) ² − (20) ² = 2(a) (0.1)

a = −(400/0.2) m/s²

a = −2000 m/s²

Thus, retardation = 2000 m/s²