How to Make an Easy Mousetrap Car (With Mods for Distance & Speed)

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Plus, learn about the science concepts that power your car
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A mousetrap car makes for a great science project, physics classroom experiment, or a fun weekend activity. Mousetrap cars are frequently used to help students learn about mechanics, force, friction, speed, and other physics topics, with many teachers turning the experiment into a long-distance challenge. We’ll show you how to build a basic mousetrap car and how to make it drive. We’ll also give you ideas for modifying your car to make it go faster or farther, and fill you in on key science terms related to the project.

Quick Mousetrap Car Instructions

Duct tape a mousetrap to a cardboard square. Screw in eye hooks on the 4 underside corners of the square and thread 2 wooden rods through the hooks. Attach 4 cardboard wheels to the rods. Tie a string to the hammer of the trap and wrap the other end around the rear axle.

Section 1 of 4:

Building a Basic Mousetrap Car

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  1. The chassis is the body of your car. Usually, this is made with thick cardboard. To accommodate your mousetrap, you'll need your chassis to be about ½ inch (13 mm) bigger than your mousetrap on all 4 sides. Measure and mark this out on your cardboard, and then use your utility knife to cut out your chassis from the cardboard. Or, hot glue popsicle sticks into a square, with popsicle planks going across to make a platform. [1]
    • Or, use balsa or basswood to make a light but more durable body for the car.
  2. Most mousetraps have a bar that locks the hammer in place, as well as sharp teeth. [2] Use pliers or wire cutters to carefully remove the bar as well as any sharp elements on the trap.
    • Keep the spring-loaded, square-shaped hammer. This is what powers the car.
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  3. Center the mousetrap on top of the chassis. Align it so that the hammer springs forward, where you want the car to go. Then, using duct tape, clear packaging tape, or hot glue, secure the mousetrap into place on all 4 sides. [3]
    • While taping your trap into place, you should avoid taping the spring. The spring should be found in the middle of the trap and snapper arm.
  4. These eye hooks will hold the axle rods, which are the rods on which you will attach your wheels. If these hooks are out of line, your car won't travel straight, so use a ruler to draw 2 straight lines on the underside of the chassis, one at the front and one at the back. Then, screw 2 hooks into each line. [4]
    • Double check the marks are evenly lined up with your ruler. You’ll insert an eye hook near each corner of the chassis.
    • If you don’t have eye hooks, tape a straw to the underside of the front and back of the chassis instead. Make sure the straw extends past the sides of the chassis.
  5. Cut 2 thin skewers to a length about 4 centimeter (1.6 in) longer than the width of your eye hooks, or at least 2 centimeter (0.8 in) wider than the chassis. Slide a skewer through each set of 2 eye hooks to create axle rods, which will hold your wheels. [5]
    • Eye hooks that are too thick or skewers that are too thin will cause the axle rod to pivot in its eye hook holder, which could affect the alignment of your car.
  6. Your wheels need to be perfectly circular so that they roll smoothly. [6] To cut basic wheels from cardboard or foam core, use a drawing compass or a round object, like a jar lid, and your pencil to trace your wheels-to-be onto the cardboard. In this example, we created 1-inch (2.5 cm) diameter front wheels and 2-inch (5 cm) diameter rear wheels. After you've traced your wheels:
    • Use a utility knife to cut your wheels free.
    • Wrap rubber bands around the outside edge of the wheels to give the them additional traction.
    • You might also use CDs, DVDs, and vinyl records to make your wheels. [7]
    • The size of your wheels also affects your car’s speed. Experiment with different sizes to see how!
  7. Use a sharp object, like a drawing compass or a metal skewer, to poke a hole into the exact center of each wheel (measure from the edge of the wheel straight across, then divide that by 2 to find the center). Wrap a rubber band about 0.5 in (1.3 cm) from each end of the skewers, slip the hole of the wheel onto the skewer, then wrap another rubber band on the other side of the wheel. Make sure the wheels are snug! [8]
    • The rubber bands keep the wheels in place on the axles, so that they don’t slip and slide around or roll off the axles.
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Section 2 of 4:

Making Your Mousetrap Car Go

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  1. Cut a piece of string that’s long enough to go from the hammer to the rear axle, plus about 5 in (13 cm). Carefully lift the hammer enough to slide one end of your string beneath it. Then, wrap the string around the snap-arm and tie a tight knot to secure the string. [9]
    • A general knot, like a square knot should work fine for attaching your string to the arm of your trap.
  2. Carefully pull the spring-loaded hammer back as far as it can go. Hold it down with one hand, and with the other hand, wrap the free end of the string tightly around the rear axle underneath the car. Keep wrapping and winding until no more string remains. [10]
    • Be careful! If the hammer snaps on your finger, it’ll hurt. This step is easiest with 2 people.
    • It helps to start winding the end of the string around the axle until it’s secure, then to simply turn the axle with your fingers to wind it the rest of the way.
    • Keep holding the hammer down with your hand until you’re reader to launch your car.
  3. Move your hands clear of your mousetrap car and let go of the string. The kinetic energy of the mousetrap spring will transfer through your string to your rear axle, causing your mousetrap car to travel forward a few feet, depending on construction and the length of the string. [11]
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Section 3 of 4:

Building Your Car for Distance & Speed

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  1. Making your car weigh as little as possible will help both distance and speed. Cardboard is already pretty lightweight, but experiment to see if you can shave off even more weight. One way to do this is by cutting holes in the chassis or wheels to reduce their mass. [12]
    • There’s a tradeoff, though! The lighter your car, the harder it’ll be to get traction on the ground. If it’s too light, the wheels might spin without actually catching, or your car might not be stable.
  2. 2
    Add length to the hammer to make the car go farther. Experiment with attaching a sturdy “arm” to the hammer, then tying the string to the end of this arm, rather than to the hammer itself. [13] This lets you use a longer string, which means the mousetrap will generate forward force for a longer amount of time, giving the “engine” more juice to help your mousetrap car cover a longer distance .
    • On the other hand, a shorter lever arm means the force is applied faster, making for a faster car.
  3. Wheels with a larger diameter will cover more distance with each turn of the axle, but may make the car slower. On the other hand, smaller wheels will apply force to the ground faster, giving your mousetrap car more speed , but it might not go as far. Also, thinner wheels are more aerodynamic, reducing air drag and helping with both speed and distance. [14]
    • CDs rimmed with electrical tape make great rear wheels, since they’re both large and thin.
  4. 4
    Make your car longer to make it more aerodynamic. As your car moves forward, the air pushes against it, kind of like when you swim in a pool and feel resistance as you move forward. To reduce this effect, you want your car to “slice” through the air. One way to do this is by making your car long and thin. Experiment with different shapes and designs, and focus on making the front of the car as thin as possible. [15]
    • You might even try to construct a tricycle car, with one front wheel and 2 rear wheels.
  5. 5
    Thicken or thin out the axle for speed or distance, respectively. The thickness of your axle has a huge influence on both distance and speed. A thicker rear axle will make it easier for the car to accelerate, while a thinner axle will mean the axle turns more times, resulting in a greater distance traveled. It’s a tradeoff, so think carefully about what’s more important! [16]
    • You may need to get larger hooks to accommodate a thicker axle or a larger straw. Mousetrap cars are all about getting creative!
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Section 4 of 4:

Key Science Terms for a Mousetrap Car

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  1. 1
    Energy Energy is the ability of something to exert force on other things. Potential energy is the energy something has based on its position relative to other things, and kinetic energy is the energy that a moving object has. [17] When your mousetrap car is primed and wound, it has high potential energy, which is converted to kinetic energy when the trap springs and the axle turns.
  2. 2
    Speed Speed is the distance your car travels divided by time. [18] Just like when you’re riding in a car and you measure speed by miles or kilometers per hour, you can measure your mousetrap car’s overall speed by dividing the distance it travels by how long it took to travel that distance.
    • Relatedly, velocity is the change in distance divided by the change in time. When you divide your car’s distance by the time it took to travel, you’re actually finding its velocity!
  3. 3
    Acceleration Acceleration refers to the change in velocity of an object, specifically the rate at which the velocity is changing. The faster your car goes from rest to motion, the greater its acceleration. If your car is moving at a constant speed, it’s not actually accelerating, since it’s not changing its velocity.
    • The equation for acceleration is a = ∆v / ∆t .
  4. 4
    Torque Torque is when the force applied to an object causes rotational motion. [19] With your mousetrap car, the spring pulling the string that turns the axle applies torque. The more torque, the greater the force on the axle, the faster or farther the car will travel.
    • The equation for torque is T = Fr , where T is torque, F is force, and r is distance from the center of the axle (a.k.a. radius).
  5. 5
    Inertia Inertia is the tendency of an object to resist its current state of motion. [20] Your mousetrap car is stationary to begin with, but needs to overcome its stationary inertia in order to get moving. It overcomes that inertia through the spring-and-string mechanism.
  6. 6
    Friction Friction is the force that resists two objects sliding against each other. [21] With a mousetrap car, friction occurs between the wheels and the ground, and also between the axle and the hooks. Where else do you think friction happens? The more friction that’s present, the more force and energy are needed to propel your car forward.
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Community Q&A

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  • Question
    Will this car go farther than 2 meters? How far will it go?
    Community Answer
    It depends on the size of the string. To make it go farther, I would add a stick addition onto the trigger arm to make it longer. This also makes the string longer. Increasing the length of the chassis will also help with distance.
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  • Question
    When building a mousetrap car, what is the proper way to tie the string and rubber band?
    Community Answer
    Go over the top of the axel. then loop around, making sure the string crosses over itself. Then slowly lift the arm of the trap and spin the wheels to continue wrapping it.
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  • Question
    What is an alternative to using the eye hooks?
    Community Answer
    If your dowels are thick enough, cut sections of straws and hot glue them to the bottom of the chassis.
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      Tips

      • Be sure to clear a path in front of your mousetrap car. Obstacles may break the fragile design.
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      • You may replace the cardboard body with a stronger, wooden one, but remember it will be harder to add the eye hooks and cut the wood. Use tools at your own risk.
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      • To help the self-propelled car roll smoothly, place some weight on the back or front of the car. Some recycled materials you can use include: bottle lids, cord, Blu-Tack, and eraser/rubber.
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      Tips from our Readers

      The advice in this section is based on the lived experiences of wikiHow readers like you. If you have a helpful tip you’d like to share on wikiHow, please submit it in the field below.
      • Add a metal washer onto your axle close to the frame in front of the rubber band to reduce risk of friction.
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      Warnings

      • Never try this project with a larger rat trap. If the snapper arm of a rat trap releases early, the force could easily break someone's finger.
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      • Young children should only assemble a mousetrap car with adult assistance.
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      Things You'll Need

      • Compass (for drawing circles)
      • Pencil (for drawing circles)
      • Hot glue or duct tape
      • Durable string
      • Elastic bands/rubber bands
      • Eye hooks (4)
      • Heavy cardboard or foam core
      • Mousetrap
      • Pliers
      • Ruler
      • Thin dowels (2)
      • Utility knife

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      References

      1. ↑ https://www.teachengineering.org/activities/view/ced-2705-mouse-trap-cars-engineering-design
      2. ↑ https://learning-center.homesciencetools.com/article/mousetrap-physics/
      3. ↑ https://sciencechallenge.robogals.org/wp-content/uploads/2024/09/MnC-Mechanical-Engineering-_-Intermediate_-Build-a-Mousetrap-Car-HANDS-ON.pdf
      4. ↑ https://www.learner.org/series/project-playbook-educator-edition/mousetrap-car/
      5. ↑ https://www.learner.org/series/project-playbook-educator-edition/mousetrap-car/
      6. ↑ https://sciencechallenge.robogals.org/wp-content/uploads/2024/09/MnC-Mechanical-Engineering-_-Intermediate_-Build-a-Mousetrap-Car-HANDS-ON.pdf
      7. ↑ https://www.aesdes.org/2021/04/03/design-preview-mousetrap-car-2-0/
      8. ↑ https://ideas-inspire.com/mousetrap-cars/
      9. ↑ https://www.learner.org/series/project-playbook-educator-edition/mousetrap-car/
      1. ↑ https://www.aesdes.org/2021/04/03/design-preview-mousetrap-car-2-0/
      2. ↑ https://www.learner.org/series/project-playbook-educator-edition/mousetrap-car/
      3. ↑ https://www.real-world-physics-problems.com/mousetrap-car-physics.html
      4. ↑ https://orise.orau.gov/K12/documents/lesson-plans/mouse-trap-car.pdf
      5. ↑ https://orise.orau.gov/K12/documents/lesson-plans/mouse-trap-car.pdf
      6. ↑ https://www.real-world-physics-problems.com/mousetrap-car-physics.html
      7. ↑ https://learning-center.homesciencetools.com/article/build-a-mousetrap-car/
      8. ↑ https://www2.chem.wisc.edu/deptfiles/genchem/netorial/modules/thermodynamics/energy/energy2.htm
      9. ↑ https://sites.science.oregonstate.edu/~hetheriw/energy/topics/doc/basics/basic_definitions.pdf
      10. ↑ https://jmercer.faculty.unlv.edu/Biomechanics/handouts/Torque.pdf
      11. ↑ https://www.physics.purdue.edu/outreach/docs/Inertia-Momentum.pdf
      12. ↑ https://physics.bu.edu/~duffy/py105/Friction.html

      About This Article

      Article Summary X

      To build a mousetrap car, start by making 4 wheels out of heavy cardboard or foam core. Carefully remove the teeth from the mousetrap, then fashion a chassis from heavy cardboard and attach the trap to the chassis with duct tape. Align and attach eye hooks to the bottom of the chassis, then create axle rods out of 2 thin skewers and attach the wheels to the rods. Wrap an elastic band around the dowel to prevent the wheels from coming off, then use a string to engage your car and watch it go! If you want to learn how to design your car based on the surface it's driving on, keep reading the article!

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