The question to the lab is How can the spring constant and muzzle velocity for a toy ball launcher be determined through physical measurements and energy conservation considerations? My lab group and I took our pastic ball launchers(pretty much toy guns) and shot them straight up and measured the hieght it went. We did three trails and ended with an average hight of 2.07 m. Then we were a little confused on where to go from there.. We also know the mass: 1.5 g or .015 kg We could find the PE of gravity from what we had so we started with that. PE=mgh. We got .305 J .. then what? Other equations that I've seen are KE= 1/2 mv^2 ... but how do I find the velocity? I tried to find the velocity by doing h= V^2/2g, getting 6.373 m/s I also have PE= 1/2Kx^2 written down, but I'm not sure what this gives me. When I plug The PE into that equation, I get Kx= .781. What exactly is that, and what importance does it have. What do I do withit next? Also, is there a specific equation to find the spring constand and or muzzle velocity. Did we forget to find some important data or something? Or do we have everything and I'm just not using the right equations? I feel stuck. Help? Thanks!