Catpult, energy transfer?

Ok we had to build a catapult for physics....

Its finally finsihed. But now that we have to do analysis we are stummped. We have 4 large springs atached to one end of the arm and the arm is on a pivot. Here is a picture...that illustrates it better:

http://mykg4orce.fasthost.tv/pult_pics/1.jpg

http://mykg4orce.fasthost.tv/pult_pics/5.jpg

http://mykg4orce.fasthost.tv/pult_pics/6.jpg


What formula will I have to use to calculate the force exerted by the arm.

Complete pictures:
http://mykg4orce.fasthost.tv/pult_pics/index.html

Hi!!

Try using the simple formula F = kx where k is the spring constant. If the formula cannot be used please let me know the reason

Regards
Shaunak

well i could use it...but how do i determine k....i dont know that.

Quote:

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but how do i determine k

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simple, F=kx. You stretch out the spring for a known distance x, and you measure the force. Devide those two values and you have your k. (You should of course repeat the experiment a couple of times, with different values of x)

Use the catapult to launch an object of a known weight - 1 kg and see how far it goes. It takes 1 Newton to move 1 kg by 1 meter (I think). To be more accurate you should probably arrange that the missile is released straight up, and see how high it goes.
The useful action of a catapult is a combination of how much weight it can launch and how far it can send it - so it should be more useful to measure these - and more fun.