pic: mousetrap car

this is the car i built for physics it was definetely the most overkill and took first place. the grading criteria was the total distance divided by the time for the first five meters my score i won with was 11. 22 meters divided by 2 seconds. notice the waterjetted frame and .25 od bearings

Was there a list of materials you could and couldn’t use? Also where did you find someone to let you use their waterjet for your physics project? Congratz on your win.

That’s what I wanna know! I’ve got some Vex parts that could use some waterjetting. My guess, though, is that it was left over scrap?

one of our sponsors waterjets alot of parts for us and we had a batch going through so i snuck these in there it was scrap material that wouldn’t have been used.

in physics we also did toothpick towers projects and you were limited to toothpicks and wood or white glue.
each group had to build 4 towers and our group average of 243lbs easily creamed everyone elses we used somepretty advanced constructions tecniques to construct them one tower included pegs holding the toothpicks together. that right we sanded down toothpicks drill a 1/32 hole and put them in. our strongest tower held 305lbs

yeah…this kind of success is what prompted the “never go against a robotics kid” mentality in my engineering and physics classes

I built a Popsicle stick bridge once… Sort of along those lines, it held about 600 pounds. It was about 4 inches wide, and like 20 inches long.

That also prompted the “never go against a robotics kid” attitude.

I wish we’d have more competative physics projects. We have to build a solar powered house (read hook up a solar cell to a few circuits with LEDs and resistors)…

nice job on that, i’m sure you deserved the win. robotics kids always win. I, the only “robotics kid” in my physics class, have won two* of three competitions so far PLUS the final competition will be a Vex challenge. i hoping to take the cake.

my egg-drop win is controversial*… :wink:
**of couse, ther was no un-gracious professionalism involved

physics got me into FIRST: I spent winter break in our lab building a rube goldberg. it was entirely over-engineered: in a class where most kids used cardboard and duct tape, we had welded aluminum and old robot batteries. it also weighed fifty pounds. after spending so much time in the lab, i figured i’d just stick around for FIRST season!

Even for theatre, we’ve accidentally gotten the “don’t mess with the robotics guys” mentality going. One of the people in our close-knit electronics group has been a techie for the last 2 years, and somehow, the entire group got sucked into the musical this year.

Collectively we ran sound (12 wireless mics!), lights, and running crew. More robotics-esque, we fixed 4 wireless bodypacks that had broken a few years ago, built signs that were no more than battery powered vision targets, wired up (safely) 10 strings of 100 christmas lights for a sign, and using hand tool skills developed over the last 3 build seasons, built 4 flats in the time it took the 3rd year techies to build one, and took down 6 platforms in the time it took them to take down one.

Yup, I’d say that robotics does teach you a thing or two that you can apply to other things in life.:stuck_out_tongue:

Sweet mousetrap racer! Thing mustve flown… too bad you didnt have a cam.

Reminds me of when I built an autonomous vehicle for my 7th grade science fair from scratch… my first robot ever and it still won FIRST place in my school as well as the state regional for my division in engineering…

And two years before that in 5th grade the shower-temperature-monitoring device that told you if your shower was hot enough and warned you with a loud beeper if it was getting too hot… that one took FIRST at my school then third in the 6th grade engineering division (yeah a year above me)…

Anyhow, yeah, never go against robotics kids in engineering/physics/science classes. :yikes:


i remember when i built a mousetrap car way back in gr 8. it was fun…except my car stunk. interestingly enough, though, one of the best cars actually used magnets to hold the axles in place, therefore almost zero friction. mousetrap cars were fun, but robots are way better. :slight_smile:

Fellow 1138 members Jeff Kane and Evan Molenda made a sick Carbon Fiber / Balsa mousetrap car, that went for 30 seconds or so, and went like, across our cafeteria diagonally, it beat everyone by 4 or 5 times. Nicely done, i like the waterjetted part

I was hoping to see those cnc’d hard drive wheels you talked about in the other thread.
Of course, the water jetted chassis is even more awesome.

I had to make a rubber band powered car for a class project/contest my first quarter in college. I made the frame from soldered brass tubing. The car won in my class, and then took first place in the competition with the other classes. So, it beat about 50 other people I think. It went from starting position to twelve feet away in 1.1 seconds. Although, these days, I hear some are running in the high 0.9s

OK, so all this gets me thinkingf: What makes a winning mousetrap car?

Well, if F=ma, and F is fixed, to maximize a we need a small m. Right? So I conclude the way to get the most is to have the smallest mass possible, all else being equal.

Yes, one must ensure the drive system is suitable - the string pulling the axle, the friction between the wheels and the ground, all that needs to be good, but there’s a wide range of ‘just fine’ there. Also, you need to bring friction down to a negligible factor - those bearings are sick, but quite right.

If the CDs used as wheels could be swiss-cheesed, you should be able to get a lot better. Can you cheese the trap, too? (no pun intended).


this mousetrap car was optimized for the grading scale(total distance/5m time)
by having the string pull on a cone that i actually managed to thread. this enabled the car to have the best acceleration in the class and the furthest distance due to its very low rolling resistance.

Don, while all of this is true…some contests dont just feature how fast the car is, but how far it goes too…which means you want o maximize distance (x or s).

That is sweet… Your probably the only person that I know of that has ever used a water jetted frame on their MOUSETRAP CAR!

the “don’t go against a robotics kid” came about in my physics class when we built trebuchets. they could weigh no more than 10 pounds - minus the counterweight - and had to throw a golf ball. Mine threw the golf ball 290 feet. Next closest was 150 feet (by a fellow robotics kid)