Question

A bullet fired in to a fixed target loses half of it's velocity after penetrating 3 cm . How much further will it penetrate before coming to rest assuming that it faces constant resistance to motion

Answer 1

x = 3cm 
v = u/2
v^2 = u^2 + 2ax
on solving this u will get,
a = -u^2/8    ......... (1)
after penetrating,
v = 0
initial velocity = u/2

v^2 = u^2 + 2ax
0 = 1/4 - (2/8)x
x = 1cm 
so it will penetrate 1cm before coming to rest

Answer 2

Answer:

1.0 cm

Explanation:

x = 3cm  

v = u/2

v^2 = u^2 + 2ax

on solving this u will get,

a = -u^2/8    ......... (1)

after penetrating,

v = 0

initial velocity = u/2

v^2 = u^2 + 2ax

0 = 1/4 - (2/8)x

x = 1cm