In our physics class, as an addition to the the already abundant car projects we had already received, our teacher assigned yet another involving hot wheels and rockets. Hence the "rocket car", which was was made to go through a series of photogates, or speed measurement devices, so that the velocity (or average speed) of the car could be found. With the data from the photogates, we calculated the acceleration and velocity of our hot wheels cars, which ended up going faster than you'd think. However, we didn't use just one photogate, but 5, so the instantaneous speeds could be used to calculate the acceleration.
Unfortunately, our class ran out of time, and not all of our data was saved. However! We did want to post our most entertaining (and slightly dangerous) lab for all you instructables fans to see. =)
The data for my team is posted in thr last step.
Step 1: Modifying Your Hotwheels Car!
Ok, so you need a hotwheels car, which are pretty cheap if you don't have one lying around your house somewhere. They're sold for about a dollar at target or walmart, and if you're buying one, get two or three, just in case your car falls apart on the first couple of runs (like ours did). Be sure to pick a car with a bit more weight to it, as it might be more inclined to stay on the track. Look at the wheels of the car to, and keep in mind that friction plays a part too.
After you get your car(s), figure out where you're going to punch some holes into the thing. If you're thinkin' "WTF what holes?", it's ok. On the track, which you'll build later, there are going to be two lines of string running down the track to stablize the car as it runs down the track. These holes are where the string is going to run through the car. So get a drill, and cut a hole wherever you think makes sense. The position of the hole WILL be different depending on the hotwheels.
After the holes are made, then get either a straw, some thin tubing, or even the shaft of a plastic pen. Then insert it into the holes you just made. Just for clarification, you'll need two tubes for the TWO holes. I didn't really specify in the previous paragraph so I'm doing it now. YOU WILL NEED TWO HOLES AND TWO SHAFTS OF TUBING. The tubes should be about 2 inches long, a little longer depending on the length of your car, but it shouldn't vary too much. You may have to adjust the size of your HOLES according to the size of the tubing you use. So when all this is figured out, get your yer'self a hot glue gun and go crazy on that hotwheel! Make sure the shaft of tubing is VERY secure, cuz' you don't wanna have it moving too much during your actual runs.
O K, now that you have your tubing in order, it's time to attach the rocket! You can pretty much put it anywhere you want, as long as it's facing the right way, and it's ON the car. We used A-E rockets, so refer to the picture above if you haven't heard of the rockets and need a visual representation. Make sure the rocket is facing the right way, and by "right" I mean with the hole facing the back of the car. Other than that, do whatever you feel is best. After you pick WHERE you want your rocket to go, then you can either zipt tie it to the car, or hot glue it, which works pretty well. However, the glue may melt from the heat of the rocket, so the zip tie might be a good idea for extra support. Depending on the height of the car, a zip tie may not work, as it might hit the ground before the wheels do, which is (obviously) bad.
So there you go....ze car iz dun.
*Making a second car is reccomended. Just in case ;)
Step 2: Duh TraK
Now that your car is ready, it's time to build the track! You'll need a plank of wood approximately 5 ft long, and 5 inches wide. Then, when you got your wood, get two L brackets and screw them onto each end of the wood, with the L facing up so that the bracket acts as a barrier for the oncoming car.
Next, if there aren't any holes available for use on the bracket, punch some in using a drill or whatever you see fit to use. Get some 10 gauge aluminum wire, about 6-7 ft long, and tie it to the end of each of the brackets. Maeks ure the string is VERY tight, otherwise it'll wobble and srew up your data when you run your car on the track. After the first wire is set, run another wire parallel to the first.
And voila! Duh TraK is dun.
Step 3: Light It Up!
Alright, now for the fun part: Data Collection!
Get five photogates. Your school may supply them, but most likely not, so you'll probably have to purchase them online. After getting the photogates, take your track and go outside. Set the track in a nice open area, preferably a parking lot or an open field, then set up your photogates. They should be positioned at about every foot along the track (see picture in step 2 for a viual). Use some clamps from your science lab to hole them in place, or make your own apparatus if you feel like it. just remember that the photogates should be ABOVE the track.
When your gates are in their respective postitons, daisy chain them together so that they're all connected. Then hook up the Vernier software port to a computer (outside, so you'll need a laptop). After, take the cables from the photogates and hook the last one into the Vernier port. As a side note. make sure that the Vernier software IS installed on the computer you're using. You can't get any data without it.
Ok, so when you're all hooked up and ready to go, set one of your cars on the track (with wires running through the car shafts of course, and get a car battery. Get a fuse to light your rocket, and clip some wires onto the wires of the fuse. Once those are in place, then you should just be able to touch the car battery witht the other ends of you (longer) wires attached the car, and there you go, the car should zoom across the track and right into your L bracket barrier. The inertia and force created by the car, may even break your L brackets. Ours were bent during our runds, and it's surprising how such little cars can do so much damage.