Racecar Book: Build and Race Mousetrap Cars, Dragsters, Tri-Can Haulers & More
How to Make Great Racecars Friction is important for a good racecar Friction is a force that opposes motion but fric tion also keeps the wheels from spinning in place A racecar driver never wants a wheel that spins in place Friction depends on two things weight and the types of surfaces in contact Rubber is a great material because it provides a lot of friction which is why you play basketball vol leyball and tennis in rubber-soled shoes Wrapping a rubber band or a piece of a balloon around your wheels can increase friction and off your car will go Weight is a tricky thing with your car Too much weight and it won’t go very far But too little weight and the wheels will just spin in place Adding weights like coins and soda cans may actually make some cars roll farther Experiment to find the best combination to help your car go The key to science is experimentation Feel free to modify any of the plans in this book if you have a better idea you won’t know unless you try Wheels To roll you need wheels Save every round thing you come across CDs bottle caps jar lids and plastic can covers like those from Pringles cans all work well Another great source for wheels is old toys Save the wheels from any broken toy before you recycle the rest A relatively cheap and lightweight wheel can be found in stores that sell fake flowers Round Styrofoam discs are used in floral arrangements and also make great lightweight wheels You can also buy wheels at hobby stores which sell a large variety of wheels for remote control cars and planes For maximum speed and distance store-bought wheels are hard to beat Many are made from high density foam which leads to lightweight tires and great friction that blast off from the starting line But store-bought wheels take cash and planning Every 2 K O O B R A C E C A R E H T
racecar in this book can also be built with free wheels Keep a box in your room with any thing you might be able to use If it’s round save it Someday you may use it to help create world record racecars Growing up my brother and I had to hide stuff from our trash monster my sweet mom She would have been more understanding if we had just explained the benefit of creative construction Axles All wheels need axles Axles can be fixed or rotating A fixed axle is stationary the wheel spins on the axle A rotating axle is affixed to the wheel and the entire wheel and axle combination spins Regardless of type toothpicks and bamboo skewers make great axles Bamboo skew ers are toothpicks on steroids Your parents may already have these around the house They are also available at dollar grocery and big box stores You can also buy metal rods or wooden dowels at most home improvement stores They add to the cost but sometimes it is worth it for a contest Contests Mousetrap car contests are a great way for science to come alive Designing and building a mousetrap car is fun and educational Mousetrap car contests have one of two goals the fastest speed or the longest distance Modify your mousetrap car to achieve maximum results for your specific contest Another type of car contest is an edible racing battle in which the car must be made primarily from edible parts Fun educational and tasty The rules may allow for tooth picks or skewers so read the rules carefully Regardless of contest type you need to learn a little about energy so you can achieve the best results T H E S T A R T I N G L I N E 3
Energy Energy is the ability to do work And in science work means getting something to move Energy comes in two forms potential and kinetic Potential energy PE is stored energy A stretched rubber band has stored elastic potential energy Elastic materials will return to their original shape after being stretched Elastic energy is most commonly found in rub ber bands and springs You will use both to power your racecars A box sitting on a high shelf has stored gravitational potential energy Gravitational potential energy is energy an object has because of its position Climbing a flight of stairs gives you more potential energy Ramps will be used to give a few of your racecars the energy they need to go Once your car starts moving the potential energy is converted into kinetic energy KE or energy of motion The more stored energy you have the greater kinetic energy you will get out Play with a rubber band to understand this Stretch it a little and shoot it Now stretch it more and shoot it More PE equals more KE and KE means speed And speed is fun 4 K O O B R A C E C A R E H T
2 Mousetrap Cars Mousetrap cars rolling machines powered by the spring of a mousetrap are a ton of fun Car design is crucial as you shoot for a world record distance or a world record speed If you want a little more power you can even go with a rattrap Mousetrap car contests are popular events for science olympiads Participants are asked to build a car that will roll the greatest distance powered only by a single mouse trap Adding a longer lever arm to the spring is the best way to create maximum distance Other contests just measure speed over a set distance If you participate in a mousetrap car competition be sure to read the rules carefully You will probably need to make a trip to the hardware or hobby store in order to create the best racecar possible but there are a few plans that use mostly free and recycled stuff you already have around the house Take a close look at a mousetrap A mousetrap consists of a wooden base a spring a hammer a catch and a holding bar The energy of a mousetrap car comes from the spring The metal spring is coiled around the base of a square called the hammer The hammer is the part that snaps closed when the mousetrap is sprung by a cheese-loving rodent 5
