Mousetraps in Motion

Use the spring-loaded action of a mousetrap to make a real working car

A mousetrap is a stellar example of converting potential energy to kinetic energy. The spring of the mousetrap is held back with a bunch of potential energy and, once released, snaps forward in a burst of kinetic energy. What if you could harness the release of energy to power a car? We'll show you how with the Mousetraps in Motion experiment.


  • Mousetrap
  • 10" x 3.5" piece of cardboard
  • Extra cardboard
  • Scissors
  • Strong tape
  • Four compact discs
  • Three zip ties
  • Ribbon or similar material
  • Three wooden skewers
  • One straw
  • Pencil
  • Wire cutters


Preparing the Mousetrap
  1. Using wire cutters, start by removing the “hold-down bar” and “catch” from the mousetrap. The “hold-down bar” is the long, slightly hooked bar that dangles off of one end of the trap. The “catch” can sometimes look like a slice of swiss cheese or be a simple metal piece in the middle of the trap, near the spring. Don't throw the pieces of metal away, though. You'll need one of the pieces later.
  2. Again using the wire cutters, cut the lever (or hammer) leaving only one side. The lever is the metal piece that threads through the spring. Be sure not to cut the spring lever.
  3. Use a pair of scissors to cut an 8″ piece of wooden skewer.
  4. Attach the skewer to the cut piece of lever on the mousetrap with strong tape. Make sure the skewer and lever are securely fastened.
Attach the Mousetrap
  1. Position the mousetrap so that the end of the trap is lined up with one end of the 10″ x 3.5″ piece of cardboard. This is going to be the back of your car.
  2. Use a strip of tape around the middle of the mousetrap to attach the mousetrap to the cardboard. 
  3. Use two zip ties, one at each end of the mousetrap, to finish securing the mousetrap to the cardboard.
Preparing the Axles
  1. Use scissors to cut two wooden skewers into 5″ pieces.
  2. Find a piece of metal that you trimmed off of the mousetrap. Make sure that it's long enough to bend. From the metal, make a shape that is a hook on one side and has, at a right angle, a straight piece.
  3. Tape the piece of metal to the middle of one 5″ piece of skewer. Make sure that the straight side is pointing straight off of the skewer.
Attaching the Axles to the Base
  1. Use scissors to cut four, 1″ pieces of a drinking straw.
  2. Tape the pieces, two at each end, to the cardboard base and thread one 5″ piece of skewer through each end.
Making and Attaching the Wheels
  1. Use scissors to cut cardboard into eight 1.5″ diameter circles.
  2. Place a cardboard circle on the middle of each side of four compact discs and tape them in place with strong tape.
  3. Push a wheel onto each side of the axles. Push each wheel 1/4″ onto the axles.
Making the Engine
  1. Measure a strip of ribbon (or similar material) from the end of the lever to the metal piece on the opposite axle and cut it with scissors.
  2. Use tape to secure the ribbon onto the end of the lever. Make sure it is secured very well.
  3. Tie a loop in the loose end of the ribbon.
Start Your Engines…
  1. Put the loop of ribbon around the metal piece of the front axle.
  2. Holding the ends of the front axle, wind the ribbon towards you.
  3. Set the racer on the ground, and let go of the axles.
  4. Zoooooooom… the lever pulls the ribbon and unwinds it, driving the axle and the car!

How Does It Work?

Whew! It took some effort, but the Mousetraps in Motion experiment was totally worth it! As you wind the ribbon around the front axle, you are creating potential energy that is stored in the spring of the mousetrap. Releasing the axle also releases the spring, converting potential energy into kinetic energy. The spring pulls the ribbon and unwinds it from the front axle, making the axle spin and pull the rest of the car along. It's just like a front-wheel-drive car!