Mouse Trap Cars

History:

James Henry Atkinson, an ironmonger from Leeds invented the design of the first mousetrap. He was born in 1849 and the mouse trap was invented in 1897. The prototype was called the "Little Nipper." To this day, none has ever been able to surpass the recoil of the spring. The concept has not evolved or changed much over the years. Even though it is a very simple trap, it is still as effective as it was when it was first created.

This is James Henry Atkinson's design of the "Little Nipper."

How It Works:

There are 5 parts to a mousetrap:
1. the platform
2. the hold down bar- this hold stoa hammer (lever) down
3. the hammer (lever) to kill the mouse
4. the spring-provides mechanical energy
5. the catch- to hold the bait


This mousetrap was a simple but effective design. It consists of a wooden base upon which sits a simple spring mechanism. It also contains wire fastening. In order to set it, you need to bring the lever all the way back. Then you have to take the hook and attach it to the other side. To attract the mice, but some sort of bait on one end of the mousetrap. When the mouse goes for the bait, the movement triggers the spring to release the lever to kill the mouse.

Mousetrap Cars:

A mousetrap car is a vehicle that uses a mousetrap as a motor or as a means of propelling the car. The most common way for making a mousetrap car is to attach an arm to the lever of the mousetrap. Then tie string to the end of the lever and wind the other end of the string on to the axle of the car. By winding the string around the axle the mousetrap's spring is activated and now you have stored energy. As the mousetrap car is released, the mousetrap pulls the string off of the axle causing the wheels to turn and propel the car forward.

A drawing of a mousetrap car

A mousetrap car is a car powered only by a spring loaded mousetrap. The mousetrap holds elastic potential energy. It is attached to a string, which is wound around the axle of the back wheels. The spring of the mouse trap wants to return to its original position. As a result of this motion, the attached lever transfers from potential energy into kinetic energy. As the string unwinds around the axle, the wheels begin to turn and the car begins to move forward.

Friction:

Another important consideration that has to be taken into account is friction. Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. Friction occurs when any two surfaces slip, slide, touch, or move against one another. There are two main types of friction: surface friction and fluid friction (air resistance). An example of surface friction is shown below. 

Surface friction occurs anytime two surfaces touch or rub against each other. When looked at under a microscope, nothing appears to be smooth even though it may seem that way when looking at it. The amount of friction depends on the materials in each object and how much force is applied to each object. An important concept for surface friction is that it will always take more force to start an object sliding than to keep the object sliding. Surface friction is also unaffected by speed. 

Surface Friciton

Fluid Friction

This is an example of Fluid Friction or Air Resistance.

In general, the more moving components that a machine has, the greater the total force of friction is.

Friction plays an important role in a mousetrap car. Without it, the mousetrap car would travel forever. The goal when building a mousetrap car is to design a car that has the lowest rate of energy loss to friction. The number one point of friction on any mousetrap car is where the axles come into contact with the body of the car.

Friction at the Axle points depends on:

• The diameter of the axle
• The pressure on the axle by bearing
• The types of material used for the axle and bearing.

Reduction in the surface are of where the axle is resting will also help to reduce friction. The use of lubricants can also help reduce friction. 

Weight and Mass:

Another factor that should be taken into account when building a mousetrap car is the mass/weight. Since the spring is only able to generate a limited amount of force, every effort should be made to minimize the weight of the car.  In theory, the lighter the car, the easier for the spring to initiate the forward movement of the car.  The heavier the weight of a car, the greater the amount of energy that is required and wasted just to initiate the early forward movement. It is advantageous to build a car that is light in order to capitalized on this early movement and allow it to accelerate