Question

a bullet fired into a target loses half of its velocity after penetrating 3 cm. how much further it will penetrate before coming to rest assuming that it faces constant resistance to motion

Answer 1

If you consider the motion of that 3cm journey of that bullet,

then lets say the bullet hits the target at speed v, then at the end of 3cm, its speed is now v/2
can u evaluate the acceleration?!

Answer 2

Work = force x distance
Work = change in energy.
kinetic energy is (1/2) m v^2
going to v/2 means having 1/4 energy, thus losing 3/4 of original
losing 3/4 in 3 cm means losing 4/4 = all in 4 cm.

Answer 3

if it has constant resistance and has lost half of its velocity 3cm in, you would assume after 6cm, it would come to rest. correct?

Answer 4

LOL

@shalini16 gonna be so confused after reading these 3 replies.. xD xD!!!!

Answer 5

consider douglaswinslowcooper`s approach

Answer 6

losing half the velocity is losing 3/4 of its energy as only 1/4 remains
work = energy change