# The Physical Science of a Gun

### The Physical Science of a Gun

Lirio Garcia Physical Science E. Martin December 13, 2012 Project: What the physics are of shooting a gun Shooting a gun is mostly the science of motion in the scientific world. One thing that most shooters are aware of is what bullet they want to use and where they want to shot at but most do not know how the gun and bullet work together or even separate. Also, there is no set balance of energy for every gun since the efficiency is mostly based on its structure of caliber and barrel length. While doing my research I have gain knowledge on not only how the gun works but the physics of it as well.

I will be discussing what I learned as well as the physics and the physics of the bullet as well when shot up in air. Some topics that I did not know that dealt with shooting a gun are friction, force, conservation of momentum (which helps characterize an object’s resistance to change in motion), velocity, kinetic energy, transfer of energy, gravity, heat engines, kinematics (analyzes the positions and motions of objects as a function of time), sound, and projectile motion which all work together to make the bullet hit the right target. Also, I was not aware that gun recoil has two parts.

Which are primary recoil from the escaping bullet and secondary recoil from the escaping gas behind the bullet. According to Samuel Hokin, the first recoil conserves momentum of the gun-bullet system while the second recoil is larger and comes after when the bullet leaves the gun one is using. Momentum’s equation is p (momentum) equals m (mass) times v (velocity). An example of an equation for momentum ( ) is if the bullet has a mass of 25 and the speed of 60 out of the gun then the equation would be p=25 x 60. Once multiplied, the momentum of this would be 1500.

When one pulls the trigger, it makes a force which moves the sear (the piece that holds the hammer which contains potential energy) and lets the hammer fire and is accelerated by gravity which is 9. 8 meters per second squared and by the puncture of the primer of the bullet that starts to propellant inside. After this the propellant creates an expanding gas which allows its pressure to get the cartridge’s casing bigger which then is force to push the projectile bullet out of the cartridge casting and through the barrel which then gets out of the gun.

Shooting any type of gun uses Newton’s Third Law which says that every force has an equal and opposite reaction on different objects since forces always exists in pairs. This force can be found from the equation Force = mass x acceleration. For example if the shooter is shooting a . 50 caliber they should be careful because since the recoil force of that gun is way to big then it can dislocate or seriously injure their shoulder. If one does decided to use this gun then it should be used with a muzzle brake so it could reduce the force of the recoil.

This helps by changing the bullet’s projectile motion but the conservation of the momentum will always be the same. When doing calculations for this with a mass of 20 mg and an acceleration of 100 m/s 2 Works Cited Binder, Madeline. “How Physics Affects Rifle Shooting. ” Articlesbase. com. Articlesbase. com, n. d. Web. 13 Dec. 2012. ;http://www. articlesbase. com/education-articles/how-physics-affects-rifle-shooting-1623110. html;. Hokin, Samuel. “The Physics of Everyday Stuff – Gun Recoil. ” The Physics of Everyday Stuff – Gun Recoil.

N. p. , n. d. Web. 13 Dec. 2012. ;http://www. bsharp. org/physics/recoil;. “Physics: Kinematics in One Dimension. ” Physics: Kinematics in One Dimension. N. p. , n. d. Web. 13 Dec. 2012. ;http://www. cliffsnotes. com/study_guide/Kinematics-in-One-Dimension. topicArticleId-10453,articleId-10415. html;. “Physics of Rifle Recoil :: Physics Recoil Gun Guns. ” Physics of Rifle Recoil :: Physics Recoil Gun Guns. N. p. , n. d. Web. 13 Dec. 2012. ;http://www. 123helpme. com/physics-of-rifle-recoil-view. asp? id=153487;.