How Mousetrap-powered Cars Work

Close-up of a mousetrap
Close-up of a mousetrap
Photodisc/Getty Images

If you've ever used a spring-release mousetrap for its intended purpose -- or had your finger clamped in its explosive grasp -- you know how amazingly powerful such a tiny package can be.

But did you know that the same power can be harnessed to propel a car?

OK, so it has to be a very small car, but that doesn't diminish in any way the coolness of the fact it needs neither batteries nor fuel. You power it by simply setting the trap and let it loose by springing the trap.

Lots of variations of mousetrap-powered cars have, ahem, sprung up: People have built designs with two, three and four wheels, and out of a variety of materials. Builders have reported achieving distances of close more than 300 feet (91.4 meters) with a single press of the trap.

If you're looking for a neat school project, an activity that's more hands-on than video games or a way to put those old Victor-brand traps to work on a peaceful purpose, try building a mousetrap-powered car!

This article will look at how these physics lessons on wheels work, as well as ways you can build your own and maybe even be the "Big Cheese" on your block when it comes to making things that go.

To learn about how mousetrap-powered cars are designed, read the next page.

Mousetrap-powered Cars Design

A mousetrap car designed for a distance competition
A mousetrap car designed for a distance competition
Photo courtesy of Benwildeboer

One of the things that makes mousetrap-powered cars so fascinating is their simplicity. Even though they work using principles of physics, you certainly don't need to be a physicist to build and enjoy them.

At their most basic, mousetrap-powered cars consist of:

  • A body -- usually flat and elongated to hold the mousetrap
  • A spring-loaded, conventional mousetrap -- the "engine" of the car
  • Wheels -- four are most common, but people have made modified designs with three or even two
  • Axles and axle sub-assemblies
  • String -- used to transfer trap energy to the wheels

In addition some builders have made cars that use the energy of multiple traps.

As you might guess, the materials used to build mousetrap-powered cars are light out of necessity. Foamcore board or balsa wood are often used for the body. The wheels can be off-the-shelf radio-controlled car wheels, but many builders use blank CDs or DVDs because their thin edges reduce friction.

So how do the cars work?

Simply put, they convert the energy of the mousetrap's spring into rotational energy that gets delivered to one set of wheels. A rod connected to the trap bar (the piece normally used to snap a mouse's neck) pulls on a long piece of string wound around one of the axles. As the string unwinds, it causes the axle and attached wheels to rotate. The spinning wheels push the mousetrap car across the floor.

Unlike when it's in mouse-catching mode, the mousetrap won't clamp on your finger and turn it into a throbbing purplish mess -- that is, if the trap is set up properly. Because it must pull against the string coiled around the wheels, the trap closes much more slowly than normal.

Got all that? If not, don't worry -- read the next page for information on how you can actually build a mousetrap-car.

Building a Mousetrap-powered Car

Assorted mousetrap cars used for the Southeastern Consortium for Minorities in Engineering (SECME) Olympiad
Assorted mousetrap cars used for the Southeastern Consortium for Minorities in Engineering (SECME) Olympiad
Photo courtesy of WillMcC

You can make the building of a mousetrap-powered car a truly do-it-yourself affair by scrounging up parts from around your house and maybe the local hardware store. Or you can find a kit that has all the parts and instructions included. If you go that route, look online or try your local hobby shop. You can even build one from LEGO elements!

If you build it on your own using one of the many instructional guides available online, there's a good chance you'll need some (if not all) of the following:

  • One regular mousetrap
  • Up to four CDs or DVDs to use as wheels
  • Hot glue gun and glue sticks
  • Wooden popsicle sticks
  • A piece of foam core poster board
  • A ruler
  • Retractable utility knife
  • Barrels from an inexpensive pen (such as a Bic)
  • Small diameter metal tubing
  • Pliers and wire cutter for shaping and trimming metal pieces
  • Optional: Washers, rubber stoppers and graphite powder

One exceptionally clear set of instructions for how to turn these materials into a working car is available here. But whether you decide to build your own or do it from a kit, be sure to check that you have all the parts and tools you need, then read through all the steps before you dive in and start putting those pieces together. And remember to be smart about safety when using tools such as hot glue guns or knives with your projects.

Once your mousetrap-powered car is built, then what? Don't just let it collect dust on a shelf -- go to the next page for ideas on how to have fun with it.

Fun with Mousetrap-Powered Cars

A student at Northfield School of Arts and Technology holds his mousetrap-powered car.
A student at Northfield School of Arts and Technology holds his mousetrap-powered car.
Photo courtesy of Artechschool

If you're in school (or perhaps if you teach school), one obvious way to have fun with this is to hold a mousetrap-powered car contest. A contest is also a great way to inject some fun into groups that meet regularly, such as scouts and other clubs for youth. Who knows? You might even make it an annual event.

In addition to seeing whose car can go the farthest distance, you can award the fastest car, the most-creative design, hold multi-lane races and so on.

Once you understand the basic principles that make mousetrap-powered cars work, you can experiment with different configurations to make your car go farther or faster. You might try different sized wheels, a different number of wheels and different axle thicknesses.

You can even beef up part of the drive axle and wind the initial length of your string around it to provide a lower "gear ratio" for a more spirited launch. Wind the rest of the string around the skinny part of the axle to get your car into "high gear."

Shoot a video of your mousetrap-powered car and post it to YouTube, where there's a thriving community of Victor-powered vehicle builders. You might be inspired by other builders' designs and pick up some handy engineering tips for building your next model.

For more information about mousetrap-powered cars and other related topics, follow the links on the next page.

Related Articles

More Great Links


  • "How to Build a Mousetrap-Powered Car." (March 1, 2011)
  • Donald, Larry S. "Mouse Trap car." (Feb. 28, 2011)
  • Kuhl, Bill. "Mousetrap Cars." (Feb. 28, 2011)