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Homework Help: Horizontal Projectile Launcher

  1. Oct 24, 2011 #1
    I need to build a completely horizontal projectile launcher for my physics class. I started experimenting with a Gauss rifle, but the horizontal velocity was hardly even 1m/s, even with strong magnets. I'm looking into a few other propulsion mechanisms, such as pressurized air (like a spud gun) or some sort of spring/rubber band driven crossbow, but I was trying to see if I could get any more suggestions or tutorials on projectile launchers. The projectile can really be anything, but something along the lines of a steel ball bearing would be ideal.

    And no, I'd rather not take the risks of building a coilgun ;P

    Thanks for the help!
  2. jcsd
  3. Oct 24, 2011 #2


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    I built one of those years ago. I used a half inch copper tube with a wooden dowel fitting inside. A pair of coil springs salvaged from a long-necked adjustable lamp pulled the dowel into the tube, pushing the ball bearing.

    A nail on the end of a wire was used to release the springs and at the same time open an electric circuit to an electromagnet holding a light bulb half way across the classroom at the same height as the gun. It worked very well vertically but the ball often missed the light bulb to one side or the other. The gun did not shoot straight. However, a few misses stretched out the moment and a good time was had by all. The most memorable moment occurred when the principal opened the door just as the ball was shot straight at him. It hit the floor well before hitting him and rolled out the door as he came in. This was high excitement in grade 11!

    The instant I got a hit, I shouted, "The vertical and horizontal motions are independent so I can't miss!" and the students seemed to remember it.
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