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Calculating velocity or acceleration

  1. Mar 1, 2008 #1
    for our physics project we had to build a catapult
    and our group built a kind of ballista.. if u dont know what that is it's a type of catapult that shoots out the object instead of launching it like a see-saw
    so our catapult is hooked up to a spring which you pull back.. then release it to launch a marble through a pipe
    but we need to find the velocity of our marble when it's launched
    how am i supposed to do that?

    i'm thinking i could use the spring constant somehow.. but i dont have any ideas on how to apply it

    any help appreciated guys :)
  2. jcsd
  3. Mar 1, 2008 #2
    Potential energy from a spring is calculated by the formula U=(1/2)kx^2, where k is the spring constant, and x is the change in the length of the spring.

    Plug in the values for k and x and you have a value in Joules. Then set that as equal to E(k)=(1/2)mv^2, where m is mass, and v is velocity.

    Voila, you have the initial velocity!
    Last edited: Mar 1, 2008
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