Recent content by muddy_waters

Oh right, I forgot to cancel the v0 when using the projectile equations. Thanks again!

Actually on #18 did you forget to put the velocity in the first part? 0 = xtanθ/v -1/2g...

Oh my God thank you so much. I really appreciate your help! :)

Ok so this delta x you solved for is it the total distance fired or the total distance the bungee needs to be stretched?

Going back to the energy equations, I think you missed an 'm'. It's supposed to say -2mgy right? And for the y, would that be the distance above ground at the end? So wouldn't that be 0, making Eg negligible?

So setting y0 = -0.48 I derived the following equation: y = -0.48 + xsinθ/vcosθ - 1/2g(x/vcosθ)^2 Is this correct? Now all I have to do is set the equation to zero, and plug in the x which is the given distance, and solve for v. Then from there I work backwards and use the energy eq'ns to...

I understand what you're saying but shouldn't the ground be -0.48m? The distance from the ground to where the marble is launched on my catapult is 48cm above ground level. Or is this distance insignificant enough to rule out?

Sorry I don't follow, could you explain why I need the y as well as the x?

Also in your derived equation, the velocity you solved for is initial right? Just making sure

Ok so once I have the coefficient, I will use your derived equation to solve for velocity. Then how do I find the specific range? would I use this equation: ΔDx = (V1sin2θ)/g

dikmikkel, I do not have a Newtonmeter. Are there any alternative methods to calculating the coefficient ?

Actually nevermind my previous post. Would I use the following equation: Elastic energy = gravitational potential + kinetic energy Ee = Eg + Ek If so how would I calculate the elastic constant for my specific bungee cord?

I thought of that, but the question arises as to how to fire the marble at that specific velocity?

My current physics project is to design a catapult that will launch a marble to a given distance (between 2-3m). I have successfully made one out of wood, using a bungee cord to snap the arm back after being pulled on. My question is how do I calibrate this properly? Our teacher said we need...