Gears, although are not required by teachers to be used on mousetrap car projects, could provide a vital contribution in your mousetrap car’s performance. By using gears, your mousetrap car could avail of a mechanical advantage by which a minimal input of power could produce an output of speed higher or faster than expected.

The speed of the car depends on the number or frequency of the wheel’s rotation assuming all other factors are the same (e.g. The axle wheel’s diameter). This means that if mousetrap car A’s wheels spin at 10 RPM and mousetrap car B’s wheels spin at 5 RPM, then it means that mousetrap car A will travel faster than mousetrap car B.

Now, assuming that all factors are the same, how can mousetrap car A’s wheels have a higher RPM than mousetrap car B?

This is where gears come into play. With the use of gears, you can manipulate the speed output of the mousetrap car. There are two major gears that you should remember here. The input gear and the output gear. The Input gear is the source of the torque while the output gear is the gear that will most likely be the one attached to the axle that will cause the movement of the car.

If the Input gear is larger than the output gear, you could expect the speed output of the gear reduction will be higher than the mousetrap car without gears. Why is this so?

Imagine to can lids. If one lid A is 5 inches in diameter and the other is 2.5 inches in diameter, and you rolled the two lids side by side, you will notice that lid A would have traveled twice the distance of lid B in just one rotation. Now, if we apply this to gears, when gear A, which is 5 inches in diameter and Gear B, which is 2.5 inches in diameter are connected, you will see that with one full rotation of gear A, Gear B will have two full rotations.

If we apply this theory to your mousetrap car, by attaching a smaller gear on your axle and using a larger gear as your input gear, your axle, depending on the gear ratio, will turn together with the smaller gear faster than the input gear.

You could apply this theory on your mousetrap car so that you could manipulate the output speed of the force stored in your mousetrap.