# Ex-NASA Engineer Shows How to Design a Winning Mousetrap Car

Follow these design principles to create a winning mousetrap powered car design.

Mark Rober makes really good YouTube videos. The ex-NASA Engineer is funny, goofy, but above all, really really smart. In one of his latest videos, he shows you how to make a super mousetrap powered car.

You might remember from high-school learning the principles of basic physics and then making a car like this yourself. Rober shows you how to win the mousetrap challenge as well as carefully explaining the principles behind it.

The underlying principle of mousetrap cars is mechanical advantage. A basic principle that you see in everyday things like pulley systems, ramps, and car jacks.

You use this principle in your mousetrap car, only in reverse. Rober goes and meets one of his friends and mentors Al, who is a high school physics teacher in Texas.

Al currently holds the world's record for the longest mousetrap powered car. Rober quickly learns that to have a winning mousetrap car you need a design that will deliver the smallest force over the longest distance.

Lesson number two is to reduce friction. In the case of mousetrap cars, friction happens where the wheels meet the ground and where the axle meets the car body. These are the two spots that you need to take care of.

Using ball bearings on the axles really improves the car's performance. The final principle you need to address is making your car light - this one is pretty intuitive, just don't make your car too big.

Watch the rest of the video to get the down and dirty on how to precisely apply these principles to get yourself a winning mousetrap design car or just to learn a bit more about the fascinating world of mechanical advantage.

## What makes a mousetrap car go farther?

Making a mousetrap car go as far as possible relies on a few guiding design principles. You'll want to design your car to have a light body, have large rear wheels, and you'll want to position the mousetrap as close to the front of the car as possible.

Having a light bodied mouse trap car allows for less work to have to be done by the mousetrap getting the car going. It makes the overall car easier to move.

Using large rear wheels allow one rotation of the axle to take the car a much further distance. In other words, a given length of the string from the mousetrap moves the car a greater distance.

The last note is to place your mousetrap as close to the front of the car as possible. This increases the moment arm of the mousetrap. In non-technical terms, this means that the same force from the mousetrap on each snap gets exerted over a longer string pull. When you have more string, it means more rotations of the axles, and thus your car will go further.

## What do you need for a mousetrap car?

Typically for any given mousetrap project, you'll either be supplied with a list of allowed materials, or you'll have to set out and find them yourselves. Here's a list of materials that are generally good to have on hand for the project if you do get the choice.

• Mousetrap
• Rubberized Tape (duct/electrical)
• Eye Hooks (for the string)
• Wooden dowel (for the lever arm)
• Heavy Cardboard or Balsa Wood
• Foam board
• String
• Ruler or straight edge
• Utility knife
• Pliers

## How can I make my mousetrap car better?

Making your mousetrap better probably involves optimizing it for whatever your goal is. In general, mousetrap competitions have two categories, speed and distance. If you want to optimize for speed, you'll want to design a car that exerts as much force/rotation as possible on the wheels as fast as possible. This will likely mean a shorter pull rod on the mousetrap and wheels that have a lot of grip so they don't spin in place when they are rotated quickly.

To optimize for distance, you can follow the steps we detailed above. Design a car with large rear wheels, the mousetrap as close to the front as possible, and one that has a light body.

## Is friction beneficial to a mousetrap car?

Friction is both good and bad in mousetrap car design. It's bad when it causes the axles of the car to stick and not rotated. However, it's a good thing when it causes the back tires to stick to the ground, giving you more traction and helping propel your car forward.

Via: Mark Rober