mousetrap cars and vehicles

Mouse Trap Car Speed-Trap Picture Gallery

Updated Feb 02, 2005

• pictures of speed-trap racers (all pictures are of students cars)

If you are trying to build a high torque racer you will need to think carefully about the following concepts: Energy, Power Output, Inertia, rotational inertia, friction, torque, and pulling force.

Energy is what moves your vehicle. The energy of the mouse trap racer is originally stored in the potential energy of the wound-up mouse trap's spring. The spring releases its energy and the potential energy is changed into kinetic energy of motion. Along the way energy is lost to the surroundings in the form of work (heat and sound). The idea is to reduce the amount of energy that is lost in order to increase the acceleration and have a high top speed.

Power output is how quickly the energy stored in the mouse trap is released or converted into kinetic energy, in the case of a speed trap racer there is really only one approaches to this consider when building your vehicle:

• Build a fast moving car that converts is potential energy to kinetic energy very quickly!

Inertia is the resistance that an object has to a change in its state of motion, the more inertia an object has the more force that will be required to change is state of motion. A heavy car will required more pulling force than a lighter car for equal acceleration; therefore, a lighter cars will be easier to accelerate.

• Build a light weight car!

Rotational inertia is the resistance that a wheel or rotation object has to changing its state of rotation. Similar to inertia but dealing with a rotating object. The less rotational inertia that an object (wheel) has the less the torque that will be needed to change its state of rotation or the easier it will be to accelerate.

• Use light weight wheels!

There are two types of friction, surface friction and fluid friction. Surface friction is caused by the rubbing of two surfaces in contact with on another. Where your axle connects to the frame of your vehicle is one place that you will find surface friction on your car. By reducing the surface friction with graphite powered or ball bearings you will see an increased performance with your vehicle. Traction is a wanted surface friction that is between your vehicles wheels and the flooring, increasing your tracking will allow for greater accelerations because it will take more torque to make the wheels spin out or break loose. Fluid friction is caused by an object trying to move the air out of the way. Make your car aerodynamic so that it is easier to push the air aside.

• Use wheels that have good traction!

Torque depends on the length of your mouse trap cars lever arm and the strength of the mouse trap's spring. A long lever arm has the same torque as a shorter arm. The difference between a long lever arm and a short lever arm is that you get more pulling force with a short arm than a long arm. To maximize your acceleration you want a shorter lever arm. Keep in mind that if your arm is too short the force will be large enough to cause the wheels to spin-out, wasting energy. To minimize your acceleration you will want a longer lever arm.

• Use a short lever arm!

See the following related articles to get started:

• how to make a mousetrap powered vehicle
• making a good distance traveler
• making a good speed-trap racer