Limit speed for a bullet (free fall, gravity, friction and drag)?

Question

Ok, this question is driving me mad :S

The conditions of the movement are:
-under gravity (9,81m/s2)
-under friction and drag (air)
-just free fall (vertilcally down)

other data:
-the bullet mass is 115gr
-the aerodinamic coefficient is 0,143

What I want to know is, when in free fall, what's the limit speed of the projectile? or how do I calculate it? (in an easy way if possible hehe)

Please help T.T

well I came up with this sparc77

if the friction+drag annulates the gravity then ƒdrag+ƒfriction=m*g

The last formula I made is:

Vlim=√(m*g)/(k)

k is the drag and friction coefficient

around 37m/s - 40m/s sounds good? :S

Answer 1

Let's see if I can point you in the right direction without doing the work for you. At what speed is the friction due to air resistance equal to the accelleration of gravity? The general form of friction due to a motion through a fluid is F=-(bv).

Answer 2

If it was falling without any resistance/friction it would never reach a constant speed but continue to accelerate.