Need some help from some people if possible!
tomorrow we've got a silly house competition for Technology and I haven't done it as a qualification - and I was entered and I'm a bit lost! I thought I'd go anyway since I do Physics at A level and it might help.
Basically we're all given the same materials - and we have to create a car, it's then let go on a slope and the car that goes the furthest wins.
I was just going to ask what would be the best way to maximize the distance? I was probably going to do some working out, with simple projectiles, resolving components and kinetic energy. But I just don't know where to start.
Like for example, should I make it really light or heavy? Or any design features to let it pick up more speed? Useful equations? I'm going to assume the angle of the slope is 30 degrees.
I'd day that you have one real factor you can control here, and that is drag.
You're going to want to make it as streamlined as humanly possible, because air resistance is going to be the crucial factor. I would normally also say road drag, but as you say that the materials are being given to you, you probably won't be able to chose the type of wheels used. If the wheels have tires, pump them up as hard as possible. If there are four wheels, dump one and make a three wheeler, that will reduce road drag by 1/4.
Physics would tell us that mass will help here. The equation escapes me at the min (been 10 years since I did A-level mechanical maths and Physics), but it involves mass and gravity (you're only source of energy). So the heavier the better. So any spare materials, chuck 'em in.
Is it going to be piloted by anyone? If it is, pick the heaviest person, and get them lying down on their front, not sitting upright. If it isn't, think about making sure it stays in a straight line, if it just veers off to one side once it's let go, it'll be useless.
Probably bit late now but the only material we can use is wood. ( apart from the wheels which have rubber tyres and have different sizes. )
One of the guys wants to make the front really heavy and smaller wheels, don't know if that would work though.
Right. Feic might be able to help more with the physics side of the wheels. Using what I know from mountain biking, weight in the wheels = rotational weight which increases as they rotate. As you are looking to maximize weight, to get the most out of the gravitational forces acting upon the car, you might want to look at using the biggest (but thinnest) wheels. Any chance of filling the tires with concrete, or sand? Might be cheating though! Again, might need confirmation here that this is actually right.
Also bigger wheels will stay truer, and be less prone to uneven road surface (think about a shopping trolley going all over the place over chippings). Edit. this might contradict my 'fill the tires with concrete' bit, as that will make the car bounce all over the place. Also probably cheating, which is unfair. Still, get a good 60-70psi in those tires.
Further edit. If possible, you could also remove a little friction by sanding the tires smooth. The tires on my singlespeed bike are completely smooth in the centre and it rolls so well.
R is "make it chuffing heavy if it's going down hill".
