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Homework Help: Which Catapult would work best?

  1. Sep 14, 2006 #1
    I'm not sure if I posted this in the right thread, if not feel free to move it.

    I have been assigned to build a catapult as my physics project. I have researched a bit and saw some examples. The main purpose of the catapult will be accuracy.

    First of all, I wanted to ask you experts which of the following catapult systems will be more accurate?!

    1. We use a weight as the source of energy. Think of it as a pendulum. The weight at the bottom of the beam moves back, the beam will go forward and the projectile at the top will be launched.

    2. We use a spring rather than the weight. The spring pulls the beam to itself, then the beam will come to a sudden stop and cause the projectile to be launched.

    The only thing that really matters is the accuracy here. I need to be able to hit a target within 8 meters of the catapult.

    Another question is what effect will it have to extend the beam? Will it cause more velocity?! I was playign with this catapult idea and this idea popped that it would be cool to have the arm actually have a variable length. Will that help at all? Or is it just a waste of brain cells (I know I need to do lots of calculations)?

    Also if I were to use the spring as teh source of energy, how can I calculate the force of it and all?! I mean with teh weight it's just the pendulum...easy. Butthe calculations with the spring are kind of foggy in my head. Can someone shine a light on that too?

    Any help is appericiated :smile:
     
  2. jcsd
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