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Homework Help: Trebuchet Circular Motion -> o.0

  1. Jul 16, 2005 #1
    I make trebuchet for my physics project and i need to calculate the distance it fires and compare it to my acctual firing.

    I know how to use the non vertical equations for circular motion but i dont know which equation to use for this.

    I can calculate the projectile motion after i have the velocity.

    Mass = 2.5kg
    CounterWeight Arm lenght = 16cm (ie. radius)
    Circumpherence it travells = 1/3 of circle.

    The counterweight arm only swings 1/3 of circles circumpherence.

    All i need to know is the equation because i can use the non vertical motion equation but then i would have to guess the time it takes.

    And i want to calculate the time not guess .:))))))
  2. jcsd
  3. Jul 16, 2005 #2


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    One of the things you will have to know is the speed of the treguchet arm itself- how fast does it go through that 1/3 circumference?
  4. Jul 17, 2005 #3
    Basically i thought thats wat i need to find out using the equation.

    I used a different equation and i found the acceleration of the counterweight arm to be 8m/s/s so if the counterweight arm is 1:3.65 ratio then that means the load arm will be accelerating @ 3.65 times faster than the counterweight arm?

    If so. What other equation will i need to know to find out time and final velocity.

    I could use linear equations of motion but i thought that the circular will make a slight difference?

    So which equation would i need since i now have

    Acceleration = 29.2m/s/s
    Distance 1/3 of circumpherence (radius = 50cm) (2*pi*r = 2 * 3.14 * 50) = (314cm) (314 divided by 3 = 104cm)

    So the distance it has to cover is 104cm

    So if i have those two will i be able to find out the final velocity of the load arm?
  5. Jul 17, 2005 #4
    kk dont bother replying. Assignment due in acouple hours. :)

    Ciao all :)) I figured it out anyway
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