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Homework Help: Energy efficiency of torsion Catapult

  1. May 6, 2010 #1
    1. The problem statement, all variables and given/known data

    How would you find the energy efficiency of a torsion catapult ? (one i built for project)

    I have the Force at which im pulling the arm.
    F = 20N

    also the angle from origin to the point of release ( or when the ball leaves the arm)
    Theta = 50 degrees

    2. Relevant equations

    Energy Efficiency = Energy Output/ Energy Input
    E input =

    3. The attempt at a solution

    i have filmed the trajectory of my catapult using Video camera and logger pro software.
    i do have velocity and acceleration in both x and y directions.

    But how do i exactly find the Input energy of this particular system?
  2. jcsd
  3. May 6, 2010 #2

    Andrew Mason

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    Science Advisor
    Homework Helper

    What is the source of energy? What is the potential energy of that source before firing the catapult? What is it after it has been fired?

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