Content

• To step
• Method 1 of 3: Optimize the wheels
• Method 2 of 3: Adjust the chassis
• Method 3 of 3: Maximize power
• Tips
• Things to Consider
• Warnings

So the physics teacher has commissioned you to make a car out of a "mousetrap": create, design, and build a small vehicle that is powered by the spring-loaded action of a mousetrap to drive it as far as possible. If you want to be better than the other students in your class, you need to make your car as efficient as possible so that you can squeeze every inch out of your "car". With the right approach, it is possible to streamline your car's design for maximum distance using only common household materials. You may also be able to buy a kit of such a vehicle to save yourself a lot of effort.

To step

Method 1 of 3: Optimize the wheels

1. Use larger rear wheels. Large wheels have a greater rotational inertia than small wheels. In practice, this means that once they start to roll, they are more difficult to stop. This makes large wheels perfect for competitions where distance covered is important - theoretically they will accelerate less quickly than smaller wheels, but they will roll for much longer and generally cover a greater distance. So, for the maximum distance, make the wheels attached to the driveshaft (the one where the mousetrap is attached, usually the rear one) very large.
   • The front wheel is a little less important - it can be big or small. To make your vehicle look like a classic drag racer, opt for large rear wheels and smaller front wheels.
2. Use thin, light wheels. Thinner wheels mean less friction and can roll further if distance is what you want or need with your mousetrap vehicle. It's also important to consider the weight of the wheels themselves - any weight that isn't needed will eventually slow down your car or lead to extra friction. In addition, it is worth noting that wide wheels can have even a small negative effect on the air resistance of the car. For these reasons, you'll want to use the thinnest, lightest wheels available for your car.
   • Old CDs or DVDs work quite well for this purpose - they are large, thin and extremely light. In this case, a washer can be used to reduce the hole in the center of the CD (to make the axle fit better).
   • If you have access to an old vinyl record (for a turntable) these also work extremely well, although they may be too heavy for the smallest mouse traps.
3. Use a narrow rear axle. Assuming it is going to be a rear wheel drive car, the rear wheels will turn every time you turn the rear axle. If your rear axle is extremely small, your mousetrap car will be able to turn more times for the same length of rope than if it were wider. This translates into turning your rear wheels more often, which means a greater distance! That's why it's a sensible idea to make your axle from the thinnest material available and that can still support the weight of the frame and wheels.
   • Narrow wood dowels are a good, easily available choice here. If you have access to thin metal rods these are even better - when lubricated, they usually give less friction.
4. Create traction by roughening the edges of the wheels. If the wheels slip on the ground when the trap closes, then energy is wasted - the mousetrap spins the wheels, but you don't get extra distance. If this happens to your car, adding raw material to the rear wheels can improve its traction. To keep your weight down, only use as much as necessary to give the ends of the wheels some grip and no more. Some suitable materials are:
   • Electric tape
   • Rubber bands
   • Broken balloons
   • Additionally, a piece of sandpaper under the rear wheels at the start line can reduce skidding if the car starts to move (when skidding is most likely).

Method 2 of 3: Adjust the chassis

1. Build the lightest chassis possible. Above all, your car should be light. The smaller your car's mass, the better - every gram or milligram you can shave off your car's chassis will take it a little further. Do not try to use extra material for the chassis other than what is needed to keep your mouse trap and wheel axles in place. If you see wasted space, try removing it or, if impossible, punch holes in it with a power drill to reduce weight. You also need the lightest possible material for your chassis. Here are just a few examples that may be suitable:
   • Balsa wood
   • Hard plastic plates
   • Thin, light metal sheets (aluminum / tin roofing, etc.)
   • Building toys (K’NEX, Lego, etc.)
2. Make the chassis long and narrow. Ideally, the car should be aerodynamic - that is, it has as small an area as possible in the direction it will travel. Compare this to an arrow, speedboat, plane or spear - a vehicle designed with maximum efficiency in mind will almost always have a long, slim shape to minimize drag. For the purposes of your mousetrap car, this will mean that your chassis must be narrow both horizontally and vertically (although it will be difficult to make the chassis narrower than the mousetrap itself).
   • Don't forget to minimize drag by giving your car the narrowest and smallest profile possible. Stand on the ground and look at your car from the front to see pieces of the chassis that make the profile of your car unnecessarily large.
3. Use glue instead of nails whenever possible. Whenever possible, try to use glue in your car's design, rather than nails, pins, or other heavier materials. For example, you only have to use a few small glue dots to attach your mouse trap to the chassis. In general, the glue holds just as well as the nails, which can add unnecessary weight. Use super glue, not school glue, as the latter won't hold very well.
   • Another advantage of glue is that it usually does not affect the air resistance of your car. On the other hand, if either end of a nail is sticking out of your chassis, can it have a small effect.
4. Keep the structural integrity of your chassis in mind. The only limiting factor when it comes to how light and slim you can make your mousetrap car's chassis is its fragility - if the car is too light, it can become so fragile that the action of closing the mousetrap can break the car. . The delicate balance between reaching maximum distance and making your car unstable can be pretty tricky to get right, but be bold to experiment. The mousetrap itself will likely never break, so as long as you have extra chassis material, you are free to make mistakes.
   • If you are using an extra fragile material such as balsa wood and are struggling to hold your chassis together, consider adding a small strip of a sturdier material (such as metal or plastic) to the bottom of the chassis. This increases the structural strength of the car and limits the change in air resistance and weight.

Method 3 of 3: Maximize power

1. Give your mousetrap a long "arm" to increase leverage. Most mousetrap cars work like this: the mousetrap is 'set', a rope tied to the arm of the mousetrap is carefully wrapped around one of the wheel axles, and when the trap snaps shut, the swinging arm of the trap transfers its energy to the axle to make the wheels turn. Because the arm of the halyard is quite short, if the car is not carefully constructed, it can pull on the belt too quickly, causing the wheels to slip and waste energy. For a slower, more stable pull, attach a long stick to the arm to act as leverage, then tie the end of the string to it, rather than to the arm itself.
   • It is important to use the correct material for your lever. The handle should not bend at all under the tension of the string - this means that energy is being wasted. Many manuals recommend sturdy balsa structures or balsa reinforced with metal for firm yet light leverage.
2. Position the trap as far forward as possible. Assuming the trap is driving the rear wheels, place the mouse trap on the chassis as far forward as possible, without touching the front wheels. The greater the distance between the halyard and the wheels, the better - more distance means you can wrap more rope around the axle for net a little bit more slow and steady pulling power.
3. Make sure there is minimal friction on the moving parts. For maximum distance, you want to use as much power as possible from your mousetrap. This means reducing the friction on surfaces of your car where points slide against each other. Use a mild lubricant, such as WD-40, sewing machine oil, or a similar product to keep the contact points between the moving parts of a car well oiled so that the car "moves" as smoothly as possible.
   • All building descriptions for a mouse trap car indicate that the axle is the primary source of friction in such a vehicle. To minimize friction on the axle, rub or spray a little lubricant on each axle where it meets the chassis and, if possible, work it into the contact point by sliding the wheels back and forth.
4. If you can, use the most powerful mouse trap you can. Usually all students will have to use the same mouse trap for this task, so that each car has the same power. However, if you don't have this limitation, use the most powerful mousetrap you can find! Larger traps such as rat traps provide much more force than basic mouse traps, but they also require sturdier structures and can break the car if they close, so you may need to strengthen and adjust your chassis and / or axles.
   • Keep in mind that rat traps and other large rodent traps can easily break your fingers, so handle traps that are on edge, even if you are sure the trap is attached to your shaft and cannot snap freely shut .

Tips

• Reduce the friction on the shaft by minimizing the area of ​​the support that contacts the drive shaft. A support for the thin steel shafts has less friction than a hole drilled through a log.
• Reduce the shocks by placing a piece of sponge on the area of ​​the cheese. This prevents the car from jumping too much when the lever arm folds down.
• Axle and suspension alignment is critical to reduce friction and improve performance.
• If you buy a washer, take a CD and the axle with you to the hardware store. This increases the chance that you will get the right size the first time.
• You can see many different student projects on the "Mouse Trap Car Challenge" website.
• Increase the friction by waxing the rope with candle wax. By waxing it, the rope has a better pull on the shaft.
• Increase the friction where necessary by using a rubber band or tape around the shaft where the string is wound. The rope should turn the shaft and not slip.
• Reduce the mass by using a simple light stick as the bodywork. Reducing mass also reduces friction at the axle jacks.
• It's helpful to make sure your axle doesn't wobble or it will move left and right.
• Use as little mass as possible on the car while still making it big enough to move.

Things to Consider

• Wheel / axle ratio: Use large wheels and a small axle for the distance. Think of the rear wheel of a bicycle; a small drive and a large wheel.
• Slowness: How much energy does it take to start your car? A lighter car needs less. Decrease the mass of your vehicle for the greatest distance.
• Release of energy: When the energy is released slowly, the power is used more efficiently and the car will move further. One way to slow this release is to lengthen the lever arm. A longer arm travels a greater distance and creates more rope around the axle. The car continues, but slower.
• Friction: Minimize the friction on the shaft by minimizing the contact area. In this example, a thin steel bracket is used. In the beginning, a hole was drilled through a log to hold the ashes. This was omitted because the increased surface area allows the car to use energy to overcome friction instead of moving forward.
• Traction: This is friction that you use to your advantage. Friction should be maximized where necessary (where the rope wraps around the axle and where the wheels come into contact with the floor). Slipping ropes or wheels equals wasted energy.

Warnings

• There is a limit to the amount of energy available: the force of the spring. The car pictured is close to the maximum. If the lever arm had been longer, or the wheels were bigger, then the car would do not move at all! In this case, the energy output can be "tuned" by slightly pushing the antennas (shortening the handle).
• Mouse traps are dangerous. You could break a finger. Always have an adult supervise. You could be injured and the fall could break!
• Be careful with tools, sawing wood, or any harmful materials. Make sure there always adult supervision is when you work on the project.