Backward recoil gun momentum balances
the forward bullet momentum to maintain zero total momentum
following the conservation of momentum.
Giancoli 2005
Conservation of Momentum: The total momentum of an isolated
system of objects remains constant.
Primary Recoil: Conserves momentum of the gun-bullet system and is noticeable by the shooter.
Secondary Recoil: The muzzle recoils further as hot expanding gas behind the bullet shoots out as the bullet leaves.
Ballistics
The motion of a projectile can be divided into three distinct phases:
-Interior Ballistics treats motion of projectile while still in gun
-Exterior Ballistics considers motion of projectile from gun to target
-Terminal Ballistics involves the projectile on the target
For external ballistics, a bullets path can be calculated using:
KE= 1/2 MV2 or KE= W(V)2 / (450,435) ft/lb
"This equation will give the bullet's energy as it leaves the muzzle, but the ballistic coefficient(BC) will determine the amount of KE delivered to the target as air resistance is encountered." BC=SD/I where SD is the sectional density of the bullet and I is a form factor for the bullet shape.
The ballistic coefficient is often used to measure drag. Drag is a function of velocity and thus the greater the velocity, the greater the retardation.
Drag (D) = f(v/a)k&pd2v2
f(v/a) is a coefficient related to the
ratio of the velocity of the bullet to the velocity of sound
in the medium through which it travels. k is a constant for
the shape of the bullet, and & is a constant for yaw
(deviation from linear flight). p is the density of the
medium, d is the diameter (caliber) of the bullet, and v the
velocity.
The greater velocity, greater caliber, or denser tissue gives more drag.