How to Build a Mousetrap Car Project

Mousetraps aren't just for catching rodents.

One of the more popular projects offered in high school physics classes is the mousetrap car, in which students build a model car powered by a mousetrap. Students have developed many designs, but the basic mousetrap car is simple to make. This project teaches principles of physics and how they can be applied.

Things You'll Need

• Mousetrap
• Two pens
• Four eye hooks
• Four CDs
• String
• Clay or axle clogs

Instructions

1. Hollow out the pens by removing the ink holders and cutting out the back of the pens so you have two cylinders.

2. Slip an eye hook around the cylinders and gently spin them to test for friction. There should be enough room for the cylinders to freely spin, but they shouldn't be so loose that they rattle, which wastes energy. Bend the eye hook until you have it as tight or as loose as you want.

3. Use an eye hook to poke a small hole in the middle of one of the cylinders. This cylinder will become the axle for the end where you place the motor.

4. Screw two eye hooks into the back edge of the mousetrap, one near each corner of the trap. Screw the other eye hooks on the front edge of the mousetrap in a similar fashion.

5. Feed your string through the hole that you poked into the axle, and secure it with a large knot or small item so it won't pull back through.

6. Feed your other axle through the eye hooks and adjust the hooks so that the axle sits level and can freely spin.

7. Place a CD on each end of the wheel you've inserted into the eye hooks. Use clay to clog the holes so that the CDs are attached to the axle. Let the project sit long enough for the clay to harden.

8. Feed the second axle through the second set of eye hooks and pull the string through so that the string hangs between the eye hooks. Secure the wheels as you did in the previous step.

9. Tie the loose end of your string on the bar portion of the mousetrap.

10. Pull back the bar portion of the mousetrap like you're setting the trap. Spin the rear axle so that the loose string winds up around the axle. Set your project on the ground and release the trap. The mousetrap will slowly pull the string, which will cause the rear axle to turn and propel the car.

Tips & Warnings

• This project is used in physics classes to demonstrate many aspects of science, such as gear ratios, friction and potential energy. Applying these lessons to your mousetrap car can increase its speed and distance.

Resources

• Mouse Trap Car