For our Honors Physics class we were required to test out how fast Hot Wheels cars would go (a.k.a. the speed or velocity) when strapped to a C-class rocket. The process went smoothly, but the actual experiment went a little different than expected...
**NOTE** In this Instructable, there are two different tests. The steps for the second test will be under the first steps so if you read both it may be a bit repetitive. The first test did not work, so I would advise using the second. But even then it didn't work, this is just a requirement for our class.
Step 1: Materials for Testing
-C Class Rocket with ignitor
-Hot Wheels or Matchbox Car
-Hot glue (and hot glue gun)
-Plank of wood (At least 18 feet long)
-Vernier photogates and wires
-Computer with vernier program installed
-Square PVC pipe
-Wire with clamps on one end
Step 2: Setting Up the Car
We used a fire rescue ambulance from Matchbox that had doors that opened to the back. We removed the seats and crushed the back frame a bit, and shoved the rocket in. It was secure enough that we didn't need any glue. Then we took the tube from a pen and cut it to the right length and glued in on top of the truck (The tube will be used in the test). Attach a zip tie on top for height. Attach an ignitor into the rocket and put in a plug and your car is done.
For the second car, (if you don't have that rescue fire truck) we used electrical tape to fasten the rocket and the tube to the car. We then used hot glue under the tape to make sure it was secure. Other steps are the same as above.
*NOTE!* Make sure the wheels touch the ground and still roll, otherwise the friction from the tape or the zip ties will keep the car from moving very far... (one car burned a hole in our L bracket!) Also that the weight of the car is not too heavy, or else the friction will be even greater (and you might wind up with a hole in your L bracket too!).
*NOTE*! You might not want to use the zip ties for height. They are very flimsy and may bend down. Paper Clamps are a better, more stable height material.
Step 3: Setting Up the Test Site
With the long plank of wood, mark off meter intervals (we marked up to a distance, and also the displacement, of 4 meters, but we had a little extra room at the end). Attach the L brackets to the ends and set up the vernier photogates at each meter interval. Feed a wire through the tube on the car and L brackets and tighten it up so the wire is taut. Hook the clamps on the wire to the ignitor wires *DO NOT TOUCH THEM TO THE BATTERY AT THIS TIME*
For the second test, we used the same track, but this time we had square PVC pipes with the top cut out drilled onto the board. Fasten the car the same, but this time use something circular or twisting to get the wire as tight as possible. Same steps as above otherwise.
SETTING UP PHOTOGATES:
To set up the photogates, put them at the correct height that's just high enough that the zip tie on your car can go through it and the correct distance (at every meter). Daisy chain the gates together with the cords included, and attach the end to the vernier collector, which will be connected to the computer.
Step 4: Testing
Put on your safety goggles, it's time to test! No seriously, put on your safety goggles. Make sure every photogate is working by testing them indiviually a few times. Push collect data on your vernier program and trigger the sensors. When you feel they are working properly, you may begin.
Push collect on your program to begin collecting data, and station yourself by the car battery. Touch the wires to the battery and watch the force of the rocket shoot the car off to the goal. DO NOT go towards the rocket until it "explodes" where it lets off excess flames shoot out the front of the rocket. You should have 10 data points on the program, and from that you can find your data (acceleration and average speed). It would be really cool if you could calculate instantaneous speed too, but I'm pretty sure the photogates don't work like that.
GOOD JOB! You're now finished and can move on with your life, just like I can right now!!! :D:D:D:D:D