Are mousetraps only good for catching mice? Think again! Building a mousetrap car is an engaging way to explore how stored potential energy transforms into kinetic energy. This classic DIY science challenge offers a fun and educational project, using the snap of a mousetrap to power a small vehicle. While it might not break any speed records, a mousetrap car is an excellent tool for learning and experimentation.
Once you’ve mastered the basic mousetrap car, the possibilities are endless. You can delve into more complex designs and modifications, pushing the boundaries of this simple yet fascinating machine.
SAFETY FIRST: Remember, mousetraps can be dangerous! A snapping mousetrap can cause injury, especially to fingers. Adult permission and close supervision are essential for this project.
Essential Tools and Materials for Your Mousetrap Car
To embark on your mousetrap car adventure, you’ll need to gather a few key tools and materials. Here’s a comprehensive list to get you started:
- Wooden Snap-Back Mousetrap: The heart of your car, providing the power source.
- Duct Tape: An indispensable tool for securing and assembling components.
- 4 Eye Hooks: These will act as bearings to hold the axles, ensuring smooth wheel rotation.
- Wooden Dowel: Choose a dowel that fits snugly within the eye hooks to serve as axles.
- Heavy Cardboard: This will form the chassis or base of your car, providing a sturdy platform.
- Rubber Bands (Large and Small): Large rubber bands for tire traction and small ones to secure wheels to axles.
- Foam Board: Ideal for crafting lightweight wheels, often found at craft stores.
- String: To connect the mousetrap arm to the axle, transferring the snapping motion into rotational force.
- Ruler or Straight Edge: For precise measurements and ensuring straight alignment of parts.
- Utility Knife: A sharp utility knife is needed for cutting cardboard and foam board (adult supervision required!).
- Pliers: Essential for removing metal parts from the mousetrap and for manipulating eye hooks.
Step-by-Step Guide to Building Your Mousetrap Car
Steps 1-8: Wheel and Chassis Assembly
1. Cutting the Wheels: Use a utility knife (with adult supervision) to carefully cut out four wheels from foam board or corrugated cardboard.
2. Wheel Size Variation: Make the back wheels approximately twice the diameter of the front wheels. For circular precision, you can use a compass or trace around circular objects like bowls or cups.
3. Adding Tire Traction: Enhance wheel grip by stretching large rubber bands around each wheel. For smaller wheels, sections of a balloon can also be used to increase traction.
4. Mousetrap Preparation: Using pliers, carefully remove any metal or plastic teeth from the mousetrap. Also, remove the metal rod that is used to set the trap. These removals are crucial for safety and functionality.
6. Creating the Chassis Base: Cut a piece of strong cardboard slightly larger (about 1/2″) than the mousetrap on all sides. This cardboard piece will serve as the car’s chassis, providing a stable base for all components.
7. Attaching the Mousetrap: Securely attach the mousetrap to the cardboard chassis using duct tape. Ensure you do not cover the central spring of the trap, especially the “snapper arm,” as this needs to move freely.
8. Installing Eye Hooks: Screw the eye hooks into the bottom of the cardboard chassis, placing one in each corner. Use a ruler to guarantee the eye hooks are aligned, which is vital for smooth axle rotation.
Steps 9-16: Axle and Power Mechanism Setup
9. Preparing the Axles: Cut the wooden dowel into two pieces, each about two inches longer than the width of the chassis. These dowel pieces will become the axles that allow the wheels to rotate.
10. Inserting Axles: Thread the dowel pieces through the eye hooks. Double-check that the axles are straight and have enough room to spin freely within the eye hooks.
11. Attaching Wheels to Axles: Create holes slightly smaller than the dowels in the center of each wheel. Then, mount the wheels onto the axles. Position the larger wheels at the back of the car, opposite the snapper arm of the mousetrap.
12. Securing the Wheels: Wrap small rubber bands around the axle on both sides of each wheel. This prevents the wheels from slipping off during operation.
13. Connecting String to Snapper Arm: Firmly tie a string to the snapper arm of the mousetrap. The string should be just long enough to reach the back axle when extended.
14. Setting the Trap (Carefully!): Carefully pull the snapper arm back towards the opposite end of the trap. You might need assistance with this step due to the spring tension.
15. Winding the Axle: While holding the snapper arm, tightly wrap the string around one side of the back axle. Wind it sufficiently to hold the trap in a set position while you place the car on the ground.
16. Release and Launch: Finally, let go of the string, ensuring all hands are clear! The mousetrap will snap shut, pulling the string, rotating the axle, and propelling your car forward.
The Physics in Motion
A set mousetrap is a storehouse of potential energy. When released, this potential energy is converted into kinetic energy, the energy of motion. The design of your mousetrap car cleverly channels this energy to the axle, causing the wheels to turn. As the trap snaps closed, it yanks the attached string forward. This pulling action creates friction between the string and the axle, forcing the axle to rotate. This rotation spins the wheels, and your mousetrap car springs into action, moving forward.
Enhancing Your Mousetrap Car Design
Your initial mousetrap car design is a starting point. It might travel a short distance, but there’s significant room for improvement. How can you modify your design to achieve greater distance or increased speed? Here are some factors to consider:
Wheel-to-Axle Ratio for Distance and Speed
For distance-focused cars, larger wheels are generally more effective. Each rotation of a larger wheel covers more ground than a smaller wheel for the same axle turn. However, initiating movement with larger wheels requires more force. If speed is your goal, smaller wheels can be advantageous as they require less force to accelerate quickly.
Inertia and Car Weight
Newton’s first law of motion, the law of inertia, plays a crucial role. It states that an object in motion tends to stay in motion, and an object at rest tends to stay at rest, unless acted upon by an external force. Inertia is this resistance to changes in motion. A heavier car possesses more inertia, requiring a greater force to set it in motion. To minimize inertia, consider using lightweight materials for your car’s construction.
Controlling Energy Release Rate
The speed at which the mousetrap releases energy significantly affects your car’s performance. A rapid energy release results in quick acceleration and higher speed, but the energy is depleted faster, leading to shorter distances. Conversely, a slower energy release will produce slower speeds but sustain motion over a longer distance. One method to slow down energy release is to extend the lever arm. Attach an extension (like a pencil or dowel) to the snapper arm and connect the string to the end of this extension. This effectively lengthens the string pull distance.
Friction Management
Friction is a double-edged sword in mousetrap car design. Analyze all points of contact where friction might hinder your car’s movement, such as between the axles and eye hooks. Reducing friction at these points can improve efficiency. However, friction is also essential for traction – the grip between the wheels and the ground. Without sufficient traction, the wheels might spin without propelling the car forward. Rubber bands on the wheels increase traction, but explore if there are even better materials or methods for optimizing grip.
Additional Ideas to Refine Your Mousetrap Car
- Durability Upgrade: Replace cardboard with lightweight wood like balsa or basswood for increased durability and reduced weight.
- Wheel Alternatives: Experiment with using CDs or vinyl records as wheels for a different aesthetic and potentially improved performance.
- Enhanced String Attachment: Instead of directly tying the string, glue a small hook to the axle and attach the string with a loop. Wind the string by rotating the wheels backwards for a more controlled release.
Unleash your creativity and engineering skills to refine your mousetrap car. By understanding the tools and physics involved, you can build a vehicle that’s not only fun but also a powerful learning experience.
