I know, I'm not exactly making a good impression by making another similar thread to those made one and two years ago, but I had some other questions. Just some background information, the assignment is that I have to construct a mousetrap car for distance (I don't believe speed even came into play for this year as a requirement). The only restriction that was clearly given to us is that we can only use the given mousetrap as the only source of fuel (no rat trap, no duel mouse traps, no Corvette). We were never even given a rubric or restrictions (he just decided to throw the packet of some of the materials at us with the basic idea behind the car and some tips), so I am assuming (heh, never a good idea) that the materials in the bag are given to us so we wouldn't have to buy the extra stuff. Since this is for distance, logically I would want a light car (less mass means less force is necessary to accelerate and move the car). I was thinking balsa wood would be most efficent for the base of the car (well, that and I am limited in the type of tools I have to work with). My concern with balsa is simply that the wood may not provide enough stability for the power of a moving (albeit, very slowly) vehicle. Something just doesn't seem right there, balsa wood seems like a simple solution for a car meant to go far. As for the axle/wheel thing, I don't think the problem is in my idea. I get the idea that big wheel to small axle for the distance racer, since the small axle will require less energy for one rotation, and the large wheel will cover more distance with that rotation. How would I be able to pull this off and power the car. I know it can be done, and if I had any experience with cars, or bikes, or whatever I could figure it out. But I can't put my finger on how the mousetrap, string (used on the loop/lever combination, which I'll get to), and axle combination works. Well, I can't figure out how the mousetrap actually moves the car, it makes no sense to me. I don't expect you guys to tell me, that was a bit of a vent, but maybe a pointer in the right direction. Wheels don't seem to be a major problem, I figure CDs work just fine, but I wonder if there's a bigger solution that wouldn't make the car unstable, even if just for the two back wheels. Styrofoam would crack, ruining a record wouldn't be very good (although that makes sense), is there a material I'm missing? As for the necessary loop/hook thing, as I said, I don't get how it works. I know that the lever connects to the mousetrap and the string is run around the axel and threw the loop. It's just so confusing, the information provided was no help. I see the diagram, I see how it loops and so on, but I don't see how it powers the car, how the mousetrap does anything. Perhaps I have to build it before I understand. Still. I figure a tensile string would be ideal, the string they provided doesn't exactly exist in New England, but I think a substitute can be found. Basically, I just want some confirmation that I'm on the right track mentally, any helpful suggestion (I'd love to gain an advantage on wheels, since that seems relatively simple if I can learn how to power the car, so a light, sturdy, material that can be shaped into a capable wheel would be nice to know about). I can answer any other questions you need to know prior to giving some advice, I have no life, so I can check on message boards often. If I found an active homework board earlier, maybe I wouldn't have broken so many pencils in frustration. Thank you.