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Creating a car using a mouse trap can be a fantastic science project, a fun physics experiment, or an exciting weekend activity. These toy cars are often used to help students grasp the concepts of mechanical efficiency, distance, and gravity. Many teachers turn this experiment into a challenge to see how far the car can travel. The potential energy stored in the spring of the mouse trap’s lever arm will convert into kinetic energy, propelling the car forward. To make such a car, you will need the right materials, a basic understanding of physical principles, and some effort.
Steps
Prepare to Begin
Visualize the Mouse Trap Car. You will need to attach the mouse trap to the car’s base (also known as the chassis) to create the frame, wheels, and engine for the car. These small car models are commonly used in physics experiments to study mechanical efficiency, gravity, and gear ratios. In this example, we will use thick cardboard to make the car’s base, but you could use the following materials instead:
- Foam core
- Old toy car frame
- A light, durable piece of wood like balsa wood
Apply Physics Knowledge for Optimal Results. You can modify your car design to achieve specific goals. For instance, if your physics class has a competition to see which car travels the farthest, you will need:
- A lightweight car body. If the body is made of dense material, drill holes in the frame and wheels to reduce weight.
- Thin, hard wheels.
- Minimize air resistance by making the front of the car narrow and smooth.
Consider the Road Surface the Car Will Run On. If your car needs to drive uphill or across rough terrain, smaller wheels will handle the incline better due to inertia. Larger wheels might perform better on flat surfaces like a table or floor.
Gather Materials. As mentioned earlier, you can use various materials to create a mouse trap car. Below is a list of additional options listed in the “Tips” section. However, to build the mouse trap car in this example, you will need:
- Compass (for drawing circles)
- Fabric tape
- A strong piece of string
- Elastic bands/rubber bands
- 4 push pins (4)
- Thick cardboard or foam core
- Mouse trap
- Pliers
- Ruler
- 2 thin dowels
- Utility knife
Make the Wheels and Frame
Create the Wheels. You need to make 4 wheels using cardboard or foam core. Use a compass or any round object along with a pencil to draw circles on the cardboard that will later become the wheels. In this example, we will use 2.5 cm diameter circles for the front wheels and 5 cm diameter circles for the back wheels. Once you’ve drawn the circles, you will:
- Use a utility knife to cut out the wheels.
- Wrap rubber bands around the rims to provide extra traction.
- You can also use CD, DVD, or vinyl records to create the wheels.
- NOTE: In this example, we will use larger wheels at the back and smaller wheels at the front.
Remove the Dangerous Sharp Teeth on the Mouse Trap’s Lever Arm. Locate the trigger bar on the mouse trap. The trigger bar typically has several sharp teeth. Carefully remove the trigger bar and use pliers to pull out all the teeth if present.
Create the Car Frame from Thick Cardboard. To attach the mouse trap, the frame should be approximately 1.3 cm larger than the trap on all sides. You will need to measure and draw on the cardboard, then cut it with a knife to create the car frame.
- Balsa wood or a wooden dowel can be used to make a lightweight yet sturdy car frame.
Attach the Mouse Trap to the Car Frame. Position the mouse trap in the center of the car frame, then use fabric tape or packing tape to securely affix all four sides of the mouse trap to the frame.
- Avoid taping over the spring while securing the trap. You’ll see that the spring is located between the trap and the lever arm.
Align and Attach the Push Pins Under the Car Frame. These push pins will hold the rods that act as axles for the wheels. The car won’t move straight if any push pin is misaligned. Therefore, you should:
- Use a ruler and pencil to mark the positions of the push pins at all four corners of the car frame.
- Double-check the alignment of the marks with the ruler.
- Screw the push pins through the cardboard at the marked locations.
Make the Axles. Cut two skewers to a length slightly longer than the width between the push pins by 4 cm. These skewers/sticks will serve as the axles for the wheels and must be thin enough to slide through the push pins and rotate freely.
- Push pins that are too thick or skewers that are too small will cause the axle to spin within the push pin, potentially affecting the car’s alignment.
Attach the wheels to the axle. You can use the sharp tip of a compass to create small holes in the center of each wheel. These holes will be slightly smaller than the sticks used to form the axle. Then you will:
- Wrap rubber bands around the axle, positioning them close to the body of the vehicle, but without touching it. The rubber bands act as a cushion between the wheel and the vehicle body, though they may create friction if they touch the body.
- Press the wheel onto the axle. The larger wheels go on the rear axle, while the smaller wheels go on the front axle.
- The axle stick should protrude from the wheel by about 2.5 cm.
Ensure the wheels stay attached and aligned. This can be done by wrapping a thin rubber band around the stick just outside the wheel. The rubber band will prevent the wheel from coming loose or shifting out of place.
Let the vehicle move.
Tie the string to the lever arm. Carefully lift the lever arm just enough to slide one end of the string underneath it, then wrap the string around the lever arm and tie a knot to secure it.
- Simply use a regular knot, like a square knot, to tie the string to the lever arm of the mousetrap.
Cut the string. Before cutting the string, make sure it is long enough to extend beyond the rear axle of the vehicle. The longer the string, the longer it will take for the trap to release, causing the vehicle to accelerate more slowly but travel a greater distance.
Prepare the drive string. The string serves as the power transmission from the spring of the mousetrap to the rear wheel of the vehicle. Reattach the lever arm and hold it steady. While holding the lever arm, follow these steps:
- With your other hand, tightly wrap the string around the rear axle of the vehicle.
- Continue wrapping the entire length of the string.
- The string needs to be tightly wrapped to hold the lever arm in place.
Prepare for a test run. Place the vehicle on the ground while keeping the lever arm held in place. Ensure the string's end is tightly held. This will keep the lever arm in position, and when released, it will snap forward and propel the vehicle.
Release the vehicle to run. Let go of the vehicle and the string. The kinetic energy from the spring in the mousetrap will transfer through the string to the rear axle, causing the vehicle to move forward for several meters, depending on the vehicle's design and the length of the string.
Tips
- Clear the path ahead. Obstacles could damage the vehicle's delicate parts.
- To help the vehicle move smoothly, you can place an object in front or behind it. Some recyclable items you could use include bottle caps, pieces of string, clay, or an eraser.
- If you don't have small skewers, you can substitute with a straw.
- You could also use toy car axles and wheels in place of skewers and cardboard, but make sure to use super glue to securely attach the string.
Warning
- Never use a rat trap for this project. If you accidentally release the lever arm at the wrong moment, the force could break your fingers.
- Young children should only assemble the car using a mousetrap with the assistance of an adult.
Things You Will Need
- Compass (to draw circles)
- Pencil (to draw circles)
- Cloth tape
- Strong string
- Elastic bands/rubber bands
- Push pins (4)
- Thick cardboard or foam core
- Mousetrap
- Pliers
- Ruler
- Thin skewers (2)
- Utility knife
