It depends on several factors, not just the size. Velocity and muzzle energy are also factors.
It depends - logically - on the caliber of the bullet, and the thickness of the pine. A deer rifle bullet will penetrate a 2x4 with no difficulty, and may or may not penetrate a 4x4. A .22 will penetrate neither, a .50 machine gun bullet will penetrate an 8x8. Loosely speaking, I would not consider pine to be a bulletproof material.
yes it can
Some can. I've seen people shoot and kill armadillos with a handgun. Some smaller calibers might not.
It is possible.
Yes
Yes, it is possible for a bullet to fully penetrate one person and also strike another person.
The penetration of a bullet in wood depends on several factors, including the type of bullet, its caliber, velocity, and the type of wood. Generally, a typical handgun bullet can penetrate wood to a depth of 12 to 24 inches, while a rifle bullet may penetrate even deeper, potentially exceeding 30 inches in softer woods. Denser hardwoods may reduce penetration depth compared to softer woods. Ultimately, specific conditions and variables will influence the exact penetration depth.
This depends on the particular caliber, weight, velocity, and construction of the bullet and the "Threat Level" of the body armor. No vest is bullet proof -- the preferred term is body armor.Generally speaking hollow points are much lesslikely to penetrate body armor which will stop non-hollowpoints bullets of the same caliber, weight, and velocity.
effective range is the distance where a skilled shooter can reliably hit a target. For 22 LR, that is about 135-150 yards. The distance at which it will no longer penetrate a skull has too many variables to give a simple answer. The bullet usually drops to below speed of sound by 100 yards, and is dropping velocity quickly after that. By 400 yards it would be unlikely to cause a serious wound.
The grains of a bullet, be it black powder or not , is the weight of the bullet. Lets say you have a .50 caliber rifle, and fire a 250 grain bullet at a target and hit dead center. Then fire a 300 grain bullet, that bullet will hit slightly lower on the target , but will have more force or stopping power" due to the weight. So the higher the grain the heaver the bullet.
A ricochet occurs when a bullet hits something it cannot penatrate.
6cm