How Not To Make A Mousetrap Car
Well, for those of you who wandered here by accident (I'm SO sorry) I will give you a brief description of what this section is for. If you are Mr. McMahon, and you are grading this, disregard this paragraph. On to the description. Well, it's my senior year in high school and I am in a physics class. Part of this physics class is a project. In this project, we have to make a car that is powered by a single mousetrap. The car is graded by how far it goes (5 meters is 100% and the grades go down from that), and speed is extra credit. On top of that, we have to make a website/lab report about the car. This section is devoted to that lab report.
I shall now tell you the secret to constructing your very own self-destructing mousetrap car of doom. We started off with a single mousetrap (surprise surprise). We then cut apart some coat hangers and superglued them to the mouse trap. These coat hangers were going to be the frame. We twisted the ends of the coat hangers into loops to hold the axles. We made the axels out of other bits of coat hanger. We then stuck the axels through the loops and poked the ends of the axels through various plastic tops (for wheels) and hot glued them down. At this point we had a car that could go no where (yay us). We needed more though. So, we pulled out the snappy arm thing that stings and replaced it with another piece of coat hanger to use as an arm to pull a piece of string. We also tied a piece of string from the arm to the axle (just long enough to have the arm extend fully). Sounds like it could work, right?
Well, to our surprise, it really did. It zoomed the farthest and at the fastest speed a mousetrap car had ever gone (it broke the current land speed record). It was so good, everyone wanted to buy it and right now we are rich and selling our very own line of mousetrap cars. NASA has offered us a lot of money to teach them our secret so they can make spaceships that are powered by mousetraps. We accepted the money of course, even though they could get our secret for free from this web site (hey, no one said rocket scientists were bright). Don't you feel special for being one of the few privileged people to get this valuable information (about $20 billion has been paid for it so far).
Okay, so that was a bit of a stretch. Here is what REALLY happened. We wound it up, brought it to the starting line (tension mounts), and let it loose. After a brief period of doing nothing, the car fell over and died. It had a few kinks to get out.
PHYSICS STUFF!!
There are plenty of scientific physics things at work, and I do not know all the terminology, but I do understand the concepts, so I will just explain those here.
The main physics concept that makes the car move (or fall over and die in the case of our car) is that for every action there is an equal, but opposite reaction. The was pulling back the spring-loaded arm and winding the string around the axle should cause the arm (when released) to spring forward, pulling on the string and causing the axle to turn. This in turn should cause the axel and wheels to turn which should make the car move. Of course, that is why OUR car is special. It defied physics by falling over and dying.
There are also some concepts that just make the car go faster and farther. One is the weight. A lighter car is easier to move and will move faster and accelerate faster. Another is air resistance. The smoother the car is, the less air resistance there is. Air resistance drags at the car and slows it down. Since these cars are so small, air resistance does very little to affect them. The last thing is friction. Friction is both good and bad. It's good on the wheels to keep them from skidding and losing precious energy from the spring. It's bad on the axle because the energy that could be used to propel the car is instead turned into heat.
PROBLEMS!!
Problem #1: As sturdy as a coathanger might sound for a frame, it is not. It practically fell off during transport. We should have superglued it back before trying to run it, but we did not have superglue or time to put it on.
Problem #2: The wheels were very floppy. So floppy in fact, they did not hold up the car at all. Well, they did at one point, but they didn't live through the transport from home to school. We should have used sturdier and wider wheels (wider is better). They would have been steadier, but we did not because we are silly.
Problem #3: The car went nowhere. This was because of two reasons. One, the string slipped off the axle without providing thrust. This could have been easily fixed by adding a catch to the axle or coating it with a high friction surface (like rubber dip). We forgot to do that cuz we were silly. The second reason was that there was no friction on the wheels to keep them from slipping. We put rubber bands on the wheels to fix that problem, but they kept slipping off and we eventually just gave up and did without them. Our initial idea for it though was to use rubber dip to coat the wheels with rubber. We both forgot to do that, and did not have enough time to put on enough coats for it to be effective. Like I said, we were silly.
All in all our car was a total failure, but at least the lab report was cool. That and we knew the main reason for why it did not work: We were silly.
click here to see some NUDE pictures of the self-destructing mousetrap car of doom
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