What is Gun: Definition and 311 Discussions

A gun is a ranged weapon designed to use a shooting tube (gun barrel) to launch typically solid projectiles, but can also project pressurized liquid (e.g. water guns/cannons, spray guns for painting or pressure washing, projected water disruptors, and technically also flamethrowers), gas (e.g. light-gas gun) or even charged particles (e.g. plasma gun). Solid projectiles may be free-flying (as with bullets and artillery shells) or tethered (as with Taser guns, spearguns and harpoon guns). A large-caliber gun is also referred to as a cannon.
The means of projectile propulsion vary according to designs, but are traditionally effected pneumatically by a high gas pressure contained within the barrel tube, produced either through the rapid exothermic combustion of propellants (as with firearms), or by mechanical compression (as with air guns). The high-pressure gas is introduced behind the projectile, pushing and accelerating it down the length of the tube, imparting sufficient launch velocity to sustain its further travel towards the target once the propelling gas ceases acting upon it after it exits the muzzle. Alternatively, new-concept linear motor weapons may employ an electromagnetic field to achieve acceleration, in which case the barrel may be substituted by guide rails (as in railguns) or wrapped with magnetic coils (as in coilguns).
The first devices identified as guns appeared in China from around CE 1000. By the 12th century, the technology was spreading through the rest of Asia, and into Europe by the 13th century.

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  1. B

    Conservation of energy and momentum in a gauss gun

    Hi, I'm doing a project on the Gauss gun and Newton's cradle. I'm trying to produce little models in MatLab and have come across some problems. Namely with the gauss gun, using different types of balls, hollow and solid (I've not even got round to adding acceleration from a magnet yet)...
  2. L

    Double-slit experiment (electron gun directionality)

    I'm having some trouble understanding why descriptions of the experiment (where single electrons are fired one after the other yet eventually forming an interference pattern) gloss over the issue of "how the electron gun is aimed" with respect to the barrier containing the two slits? One, I...
  3. C

    How Can Laser/ Light Guns Be Used for Unobtrusive Assassination Laser Tag?

    Making a laser/light "gun" Hi.. We are hoping to start a laser tag-like game that people play 24 hours/day, and it's basically a giant game of assassination laser tag that is always ongoing. However...the typical laser tag 'ammunition' won't work because it won't penetrate pockets or...
  4. M

    Thick or Thin Wire for Coil Gun: Physics Project

    I am making a coil gun for my physics project and I am wondering if it is better to use a thick wire or a thin wire for the coiling process. (both are magnetic wire) Also, when I coil it, am I supposed to make only one layer of coil as opposed to several layers? Thanks in advance.
  5. L

    Troubleshooting a Coil Gun Project Using a Disposable Camera Circuit

    I'm making a coil gun for a project, and ran into a few problems. I used a circuit from a disposable camera, which had a capacitor and charging circuit. I used two wires attached to the capacitor to connect the circuit to my solenoid. However, after charging the capacitor, nothing seems to...
  6. F

    Is it dangerous to fire a gun upwards?

    Homework Statement I am just wondering, if you fire something at some speed and acceleration, that something will come down even stronger right? So you know in funerals, often there accompanied some men in some suits and they start firing a few times in the air. Why do they do that even...
  7. B

    Increasing Laser Tag Gun Range with Convex Lenses?

    So this is the case - I've bought some shocking laser tag guns to play with my friends, though I am unsatisfied with their range which is merely 5 meters. I was wondering if I could add some convex lenses in front of the laser gun in order to increase the range of the laser, would that work...
  8. M

    Refocusing of paraxial electron from electron gun

    Homework Statement Electrons emitted with negligible speed from an electron gun are accelerated through a potential difference v along the X-axis. These electrons emerge from a narrow hole into a uniform magnetic field B directed along this axis. However, some of the electrons emerging from the...
  9. S

    Spray-on Skin gun to heal burn victims

    Amazing new tech! https://www.youtube.com/watch?v=7Y5H9Sasq5U [/PLAIN]
  10. S

    Build Gauss Gun for Semester Experiment

    For a semester long experiment, I am to build a coil (gauss) gun. I also need to hand in a paper including all equations and theory relevant to the experiment, but I have not been able to find any equations that actually work for the purposes I require. Any help to guide me in the right...
  11. C

    Horizontal Recoil Speed of gun

    Homework Statement a 1200kg gun mounted on wheels shoots an 8kg projectile with a muzzle velocity of 600m/s at an angle of 30degrees above the horizontal. find the horizontal recoil speed of the gun Homework Equations KE= .5mvfE2 - .5MViE2 The Attempt at a Solution to be honest I...
  12. F

    Projectile Motion Problem: Calculating Velocity, Distance, and Potential Energy

    Homework Statement "A 45.0 kg projectile is fired from a gun. The elevation angle of the gun is 30.0°. the projectile is in the air for 48.0 s before it hits the deck at the same height as it was fired. Ignoring friction find: the projectile's initial velocity, the horizontal distance the...
  13. turbo

    News Peter King (R-NY) to introduce gun control law

    King wants to make it illegal to knowingly carry a gun within 1000 feet of an elected federal official or judge. What's his point? If some lunatic wants to shoot a Congressman, will he be deterred by such a law? I simply don't see how such a law would give additional protection to public...
  14. BitWiz

    Calculating Ship Acceleration with Gauss Gun Propulsion

    Hi, Say I have a spaceship in ideal gravity-free, friction-free space. I have a source of power capable of producing a maximum of E joules per second, and I want to use some form of continuous electric propulsion, such as a Gauss gun or ion thruster, to get around. I have these questions...
  15. H

    Hot air gun, practical use of Faraday law

    Hello, I have the following question, I am trying to build a home made hot air gun for electronics soldering, my approach was with a modified Microwave oven transformer, multifilar 12mmxmm copper cables, and a 15cm stainless steel tube, the air is pumped from a powerful aquarium air pump. The...
  16. C

    How would the electric field look like for an electron gun?

    Homework Statement Sketch to illustrate the device and the role of the electric field for - an electron gun Homework Equations N/A The Attempt at a Solution http://i.imgur.com/J8Diu.png
  17. B

    Calculating range with controlled air gun

    Homework Statement Ultimately, I need to calculate the range of projectile fired from my controlled air gun. My meter gives me pressure in psi which i keep at constant 40 psi, allows me measure (theta) 45 degrees, volume 2.48 in^3Homework Equations R=(v^2/g)*sin(2(theta)); x(t)=v cos(theta)t...
  18. E

    Determine the kinetic energy of the electron as it leaves the electron gun

    Homework Statement In an electron microscope, there is an electron gun that contains two charged metallic plates 2.75 cm apart. An electric force accelerates each electron in the beam from rest to 8.90% of the speed of light over this distance. (Ignore the effects of relativity in your...
  19. P

    How High Does the Dart Travel When the Spring is Compressed Half as Far?

    Homework Statement A spring-loaded dart gun is used to shoot a dart straight up into the air, and the dart reaches a maximum height of 24 meters. The same dart is shot up a second time from the same gun, but this time the spring is compressed only half as far (compared to the first shot). How...
  20. A

    An idea about gun control. Let me hear you opinion

    After hearing some stories of some people about to commit suicide by buying gun and planning to kill his whole family as result of hardships in his life (fortunately he changed his mind and got over it). and some stories on news of gun shots. So my idea is What would happen if there was a law...
  21. K

    Finding the Launch Angle of an Artillery Gun

    Homework Statement An artillery gun is trying to hit a target that is 12.5 km away. If the shell is fired at 650 ms-1 at what angle above the horizontal should the gun be fired to hit the target assuming that air resistance is negligible? [g=9.8 ms-2] Homework Equations I tried using v^2_y...
  22. B

    Random questions: explain BB gun bullet dent in (regular) glass?

    Hi all, this has been bugging me so maybe you can help me out. In the front window of my house, there is a dent in the glass that looks somewhat similar to this: http://www.flickr.com/photos/guerra/2557095422/" However, there is not hole in the glass. But the shape of the dent is...
  23. P

    Mastering physics help - rail gun

    Homework Statement attached Homework Equations The Attempt at a Solution I think i need to use energy methods for this because the acceleration is not constant.. trouble is I don't know the formula for the potential energy in cases like this. Thanks for any help.
  24. F

    A beam of light compared to bullet in gun

    If a train goes past an observer at 100km/hour and someone on the train fires a bullet from a gun in the direction the train is going at 700km/hour, then relative to an observer, that bullet will go past at 800km/hour. Einstein made a statement of the type that if a person on the train holds a...
  25. D

    What are the best options for building a DIY radar gun?

    Hi guys, I have a couple of questions, 1. Is a FM transmitter for an Ipod the same thing as a FM transmitter and Reciever for a radar gun? 2. Where can I find FM transmitters and Recievers for a radar gun. Or even better parts or a kit to build my own radar gun. (link would be helpful)...
  26. C

    Will the gun explode if I do this?

    I have a couple of questions for the members of this great site. If I shoot a .45acp bullet with 230 grains in a 5" barrell in salt water at a depth of 140', will the gun explode? does the type of bullet makes any difference? for example flat head vs cone shaped? What would be the formula to...
  27. G

    The Physics Behind Gaussian Guns

    I'm sorry this is not really a school question i was just intrigued and did not now where else to ask about it. I have seen videos of these Gaussian guns and they appear to generate energy from nowhere, obviously impossibly. So what is the physics behind how they work?
  28. D

    Anyone know how I can build a FM radar gun?

    Well here are a couple of things I would like to know. Thanks in advance! how to build a Frequency-Modulated Radar gun. or how to build a Frequency-Modulated transmitter and reciever or where i can get either of these :D Thanks again!
  29. Gokul43201

    News Interpreting the 2nd Amendment: Literalism and Intent in Gun Laws

    In my layman opinion, the arguments last year (or the year before - context: DC gun law) that the second clause in the 2nd Amendment is not predicated upon the first, is at least grammatical overreach.
  30. C

    Using Ni-Chrome Wire for Heated Cathode in Electron Gun

    can i use ni-chrome wire , for my heated cathode on my electron gun , using Thermionic emission , or what would be a better filament to use.
  31. M

    Ball being shot out of a spring gun - Velocity

    Homework Statement The spring has a force constant of 355N/m. The spring is compressed 5.9 cm and the ball has a mass of 0.029kg. The gun is held horizontal. The barrel of the gun is 5.9 cm long so the ball leaves the barrel at the same point it loses contact with the spring. A resisting force...
  32. S

    Electron gun design using faraday cage like setup

    I have designed an electron gun that incorporates a faraday cage setup and I would like anyone's opinion if this setup could actually work. See attachment for image or here is a link to the image of the electron gun http://yfrog.com/j7electrongundesignbj Explanation of image There is a...
  33. J

    Ball Launched from spring gun (max height)

    Homework Statement A ball of mass m is launched at an angle theta from a spring gun of length D. The lower end of the gun, where the spring is attatched, is at ground level. The spring has spring constant k and an unstretched length D. Before launch, the spring is compressed to a length d...
  34. K

    Calculating Acceleration and Force in an Electromagnetic Rail Gun

    Homework Statement An electromagnetic rail gun can fire a projectile using a magnetic field and an electric current. Consider two parallel conducting rails, separated by 0.575 m, which run north and south. A 49.0-g conducting rod is placed across the tracks and a battery is connected between...
  35. M

    Solve Rolling Staple Gun Homework Problem

    Homework Statement An assembly line has a staple gun that rolls to the left at 1.0 m/s while the parts to be stapled roll past it to the right at 3.0 m/s. The staple gun fires 10 staples per second. How far apart are the staples? Homework Equations I am lost but I still came up with an...
  36. D

    What angle should an elctron beam leave an electron gun?

    [b]1. At what angle should a 1kV electron beam with a total current of 1mA leave an electron gun in order that the cross section of minimum diameter will occur on a screen 25cm away? The original diameter of this beam is 2mm. [b]2. Cannot find equations in book or notes anywhere...
  37. C

    Designing an air gun to launch simulated rpg's

    I am designing a simple air gun to launch a 1 kg projectile 50 m at 100 m/s. I estimated the drag & calculated the necessary angle for this, but I ran into a bit of difficulty with the pressure/valves. I need to use an air compressor at around 125-150psi to power it. I'm still a freshman...
  38. M

    Make a rail gun into a rail motor?

    I've been thinking about an idea for a while now... what if you take a rail gun set up and instead of shooting something you turn it into a motor. Just make the rails into hoops that almost touch and connect the armature to a point in the center of this. I'm wondering how armature (now a rotor)...
  39. K

    Did a Stray Bullet on New Year's Eve Kill a Child at Church in Atlanta?

    Remember that conversation in PF chat about people shooting guns on New Year's Eve? A falling bullet from one of those shots fell through the roof of a church and killed a four year old boy at mass in Atlanta. Wow. http://www.myfoxatlanta.com/dpp/news/Stray-Bullet-Kills-4-year-old-Boy-010110
  40. B

    Science Fair Project: High School Railgun Q&A

    Hello, I am a high school senior making a railgun for my science fair project. I have been searching the internet and have finally come up with a plan for my railgun. I have some questions about my plan before I go out and buy materials. I have two questions currently, one about rails and one...
  41. A

    Micro Processor project making a Gun Chronograph

    I need a little help with a lab project that I am making for my Micro Processor class. My instructor gave me the idea of making a gun chronograph. He wants me to use 4 qrb1134 reflective sensors to detect an object. The qrb1134's will be in two pairs set at a certain distance apart. The...
  42. J

    An Object coliding with a spring gun

    Homework Statement A 0.1kg is shot with a speed of 6m/s toward a 1.2kg spring gun( with spring constant of 0.4N/m). The spring gun is initially at rest with its spring relaxed. The spring gun is free to slide without friction on a horizontal table. The 0.1 kg mass compresses the spring to...
  43. C

    How Fast Does a Stapling Gun's Ram Move at Impact?

    Homework Statement A heavy-duty stapling gun uses a 0.151-kg metal rod that rams against the staple to eject it. The rod is pushed by a stiff spring called a "ram spring" (k = 35007 N/m). The mass of this spring may be ignored. Squeezing the handle of the gun first compresses the ram spring by...
  44. K

    Velocity of bullet fired from a gun

    1. Anyone interested in looking over the question / coments, thanks. An object mass 0.6kg is fired vertically upward in thebarrel of a gun by a vertical force of 50N acting over a period of 0.5 seconds. Calculate A. The velocity of the projectile when it leaves the barrel B. Height reached by...
  45. U

    Calculating Angle of Elevation & Initial Speed of Projectile from a Gun Fire

    A gun fires a projectile toward a target that is 4.54 km distant at the same elevation as the gun. The gunnery officer notes that the projectile hit the target 27.5 s after firing. a)Find the angle of elevation of the gun barrel. b)Find the initial speed of the projectile. So x=4.54 km...
  46. Q

    Physics of Verne Gun: Launching Vehicle to Escape Velocity

    A scenario recently sketched out by Brian Wang at "Next Big Feature" is to launch a vehicle to escape velocity via using a nuclear pulse, but enclosed so the fall-out can be contained. I suggested it needed a working fluid, specifically hydrogen, to provide a mechanical coupling between vehicle...
  47. O

    The Doppler Effect of radar gun

    Homework Statement You are in charge of calibrating the radar guns for a local police department. One such device emits microwaves at a frequency of 2.15 GHz. During the trials, these waves are reflected from a car moving directly away from the stationary emitter. You detect a frequency...
  48. F

    How to manually solder a QFN chip with a hot air gun?

    Hi there, I have a tiny 48-QFN chip that I have to solder manually. The pin width of the chip is .28mm and the clearance of the pins is .22mm. The pins are totally under the chip and from side I can only see little metal indicating the positions of the pins, which makes it impossible to...
  49. Loren Booda

    Is Gun Ownership Linked to Higher Rates of Violence?

    Are legal gun owners more violent than the general population?
  50. G

    Paintball impact with stonger Gun

    We went paint balling with 17 friends. At dinner we had an discussion if a stronger weapon would result in stronger hit. The question is? Is their a maximum of energy a paint-ball can give to your body, independent of speed or energy. In other words...Will a bigger gun hurts more than a...
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