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

My Mouse Trap Car

My Mouse Trap Car:

• Supplies:
• 1 Mouse Trap
• 2 Balloon
• 4 Pens
• 4 CDs
• String
• 1 Metal Hanger
• 2 Paint Stirrer
• Cardboard
• 2 Sticks of Fiber Glass
• 2 Plastic Washers
• 2 Metal Washers
• Hot Glue Gun
• Drill
• Scissors
• Saw
• Exacto knife

• Procedure:



These are the front wheels



1. Gather all the materials needed to build the mouse trap car.
2. Pull apart each of the 4 pens so that the body of the pen is completely hollow. Put the ink cartridges aside to be used later. 
3. Take one CD and lie it flat down on a table. Place the hollow part of the pen vertically in the center of the CD so  that it is perpendicular. Hot glue the CD to the pen and wait for the glue to dry. 
4. Once it is dry and the CD is secure to the pen, take another CD and lie it flat on the table. Place the pen with the already glued CD in the middle of the other CD. Once in the center, glue it again. This will be used as the front set of wheels.
5. In order to create the back set of wheels, take a piece of fiber glass and sharpen each of the ends to a point. This will allow you to get the CDs on. Take one washer and hot glue them into the center of the CD. Repeat this for the other CD. Once the glue is set, put it aside for later.

   

   These are the back wheels

6. Next, get a ballon. Fold the balloon in half horizontally and cut the two ends of the balloon off. When you have just the center left, cut it again. This will leave you with 2 separate pieces. Then unfold it leaving part of the balloon shaped like a rubber band.
7. Place the rubber band like balloons around the two of the CDs which have the washers glued into them. These will later end up being the back wheels. The balloon is there to provide friction so that the wheels have traction and actually move rather than spinning out of control. All of these steps above have just helped to create the axles and wheels to the mouse trap car.
8. Put the wheels and axles aside until the body of the car is complete.
9. Now to build the body, take a piece or cardboard that is 13 inches long and 5 inches wide. Then take another piece of cardboard that is the same length but much thinner. Take the exact knife and cut the off the ends of the thiner piece at an angle to form a trapezoid. After, hot glue it to the center of the big piece of cardboard so that they are perpendicular to each other and the trapezoid is facing down. Then, let it dry.
10. Gather both of the paint stirrer. Take one and cut it equally into four pieces. Then take the next one and cut it so that it is 8 1/4 inches long. Hot glue the 8 1/4 piece to the edge of one of the ends of cardboard. Make sure that the thinner piece of cardboard is facing down. 
11. After the glue has dried, take two of the four pieces and glue it to the ends of the 8 1/4 inch piece so that it will form a right angle. This has created the front of the mouse trap car.

    

    This is the bottom of the car

12. Flip the cardboard around so that the back is facing you. Take the last two pieces of paint stirrers and glue it to the cardboard to forma right angle. The pieces should be sticking of the cardboard about 2 inches. 
13. Next, gather the 2 metal washers. Hot glue one to each side of the paint stirrers so that the hole in the center is just below the stirrer. Theses 2 washers will help hold the back axle in place and create less friction when it rotates.
14. Now, get the ink cartridges that were put aside earlier. Cut off the ends of the pen so that only the ink is left with the plastic. Then cut off the part at the end that has no ink in it. Do this with one more of the pens so that you have two pieces of plastic without ink and two pieces with the tip still connected.
15. Grab the front wheels (the axle is made out of the pen body) and stick the two pen tips in to the hollow body. Then glue them in so that they are secure. Make sure that the tips of the pens are sticking out at each end. 

    

    This is the front axle

16. Then take the body of the car and glue the two plastic tubes to each side of the paint stirrers. Make sure that you are gluing them to the from of the car. the front This will help to secure the front axle in place.
17. Next, take the front axle and put each pen tip into the plastic tube so that it is able to spin freely.
18. Now go to the back of the car, take the piece of fiber glass that was sharpened and stick it into the center of the two metal washers. This will be the back axle.
19. Then take the two CDs with the plastic washers glued into them and stick them onto the piece of fiber glass to secure it into place. Now body and wheels of the car is complete.

    

    This is the mousetrap with the lever

20. To add the lever to the mousetrap, gather the other piece of fiber glass. Pull the hinge back and attach the fiber glass to one side of the hinge. To do this, take a piece of string and start to wrap it around until it covers the whole side of the hinge. Then put a drop of glue on the beginning and end of the string to make sure that the fiber glass stays connected to the hinge of the mousetrap. This will serve has the lever which will help to propel it forward.
21. The hot glue the mouse trap to the body of the car. Make sure that the mouse trap is at the front of the car and is perfectly entered. This will help to balance out the weight. Also, make sure that the lever is facing forward so that when it is pulled back, the car is propelled forward.
22. Then drill three holes into the mousetrap and through the cardboard. Get a piece of string and start to thread it through each hole to secure it onto the body of the car. This will give extra support to the mousetrap to that it does not detach from the body while it is moving. 

    

    This is the back axle with the hook

23. Take the metal hanger and cut a very little piece off the top. Then hot glue it to the center of the back axle. This will help the string to wind up on the axle.

    

    This is the lever with the string glued to it

24. Lastly, at the other end of the lever, saw a little indent around it to tie one end of the string to it. Then add a little hot glue to help make sure it does not move. In order to know how long the string should be, take the string and bring it to the back axle. The string should be the distance between the back axle and the front of the lever. Then tie a loop at the end of the string so that it can hook onto the metal hanger attached to the back axle.

    

    This is what the mouse trap car looks like

How It Works

         This mouse trap car works by having the spring in the mouse trap propel it forward. The spring acts like the engine in a real vehicle. When the string is being wound up around the back axel, it is building up energy for the car to move. When it is let go, all the energy is released so the lever starts to move forward because it wants to go back to its original position. The string begins to unwind around the back axle which is what is making the axle turn.  This is making the whole car move forward. With the balloons attached to the back wheels, it provides traction which helps the car stay in control. Without them, the wheels would still spin but the car would not go as far because there is less traction between the wheels and the ground.

This is a video of my mousetrap car in action: