Question

A bullet, on entering a target, losses 1/3 rd of its initial velocity, after penetrating through 20m. How far deep will it enter the target?

(1) 60 m

(2) 40 m

(3) 36 m

(4) 16 m

Answer 1

(3) 36 m

Suppose the bullet loses u/n of its initial velocity, after penetrating through distance s. So, final velocity, after travelling distance s in target, is

If a is the deceleration, then :

If the bullet goes a further distance x, before coming to rest, then

Given, s = 3m, therefore

Therefore, total penetration is 

s + x = 20 + 16 = 36