science fair help (need help fast)?

Question

well.. for my sceicne fair expiriment, i'm finding whether the counterweight on a trebuchet affects how much power the projectile flies with.
i'm testing this by launching projectiles filled with water and they break when they hit the ground. then, i measure the length of the water to see how much power it had..

only problem is, i gotta prove taht the longer the water travels, the more force it has...


lol..if that didnt makes sense, just think of it this way :
I need a way to prove that the longer mark a projectile leaves, the more power it has...

(ps, anyone have some other word besides "power" that i can use to make it more science-related)

Answer 1

Technically, the length of the mark of the projectile doesn't necessarily relate to the power - it can also be affected by the angle of impact. To compare the final velocity (and thus the force of impact), you'd probably want to measure the splatter area instead of just the length.

You can prove this by dropping water balloons from varying heights. Due to the constant accelleration due to gravity, the velocity at impact is greater as the initial height increases.