mousetrap car help center

Questions:

How long should I make the lever arm?

By Doc Fizzix // Published Nov 16, 2005

Answer:
It really depends on how you are designing your mousetrap vehicle. There is no "actual" size for how long the perfect lever arm should be. If you want speed and/or power then you will want as shorter lever arm in order to create more torque, with a shorter the lever arm, more pulling force is delivered to the drive axle. If you are building a distance traveler then you want a longer lever arm so you can wind more string around the drive axle so the vehicle can be pulled further.

By changing the length of the mousetrap's lever arm you change the pulling force, longer lever arms have less pulling force than smaller lever arms. Where you mount the mouse trap is just as important as the length of the lever arm. Where you mount the mousetrap and how long you make the lever arm really go hand-in-hand. The lever arm should only be long enough to "just" reach from the placement of the mousetrap on the vehicle to the drive axle when the string is fully wound up around the drive axle. The actual length of the lever are will depend on the design of your car.

The same concept of torque applies to the ratio of the drive axle to drive wheel relationship. Adjustments can be made to the size of the drive axle to change the torque, see the article on axles and wheels - the gearing

See the following related articles to get started:

• basic mousetrap vehicle propulsions (how to make it move)
• how to make a good distance traveler
• how to make a good speed-trap racer