Mousetrap car? What is it? Some people might have wondered what exactly the Mousetrap car is. It is a physics project in which students design and construct a vehicle with single mousetrap as its sole source of propulsion. A mouse-trap car is powered by the energy of a wound up mouse-trap's spring. Energy stored in the spring would cause the vehicle to travel in distance if it was under good construction.
The first thing we did was searching for materials. We knew that lightweight materials will make sense for a better motion. There is a wide range of choice for the car to be made of wood, plastic or lead, etc. So we adopted the materials according to our preference. Actually, we had concerned about where to get the materials, but than we ascertained that, we could find some wood at Bueng Trobek carpenters area, and Oar Reasey Market was where most of the needed materials could be found. For example, mousetrap, axle, ball bearing (known as Padarng in Khmer), string, screws, nails, etc. We needed some household equipment like driller, screw driver, hummer, saw, etc. When all the materials were in hand, we began our construction.
Initially, we created the body of the car, using our materials we had chosen, and the wheels. We formed the wheel system by axles, which could be any dowel rods, craft sticks or iron sticks that we placed in to the chassis, drilled holes on the wood, where approach to the end of the car body. Then we attached the wheels to each two end sides of the axles. After that, we located a mousetrap on the body of the car by using glue, tape or screw. Up to this step, we obtained a very simple car. In order to investigate the requirement of the car system, we tested our cars for the first time. We learned from the experiment that ball bearing is needed to apply in between the wheel and the chassis, where a lot of friction occurs. Another condition demanded we had to attach a lever arm to the mousetrap's "snapper". The purpose of the lever arm is that long lever arm decreases the pulling force but increases the pulling distance. Thereby long lever arm minimizes the power output or transfer stored energy into energy of motion at a slow rate, which explains how mousetrap car could travel slowly in great distance.
We had to wind up the string around the axle whilst we want it to get in motion. Wrapping the string around the axle can be troublesome. It requires some practice and patience. We had to wind the wheels in the direction opposite to the motion that we want the mouse trap car to travel, in this way the string winded around the axle. We have learnt some strategies in winding the string. For example, do not wind the string loosely or it will snag itself and do not push on the mousetrap's lever arm during this process, you want the string to be tight and to pull the lever arm over. Once the mouse-trap's arm is released, the tension of the mouse-trap's arm pulls the string off the drive axle causing the drive axle and the wheels to rotate, propelling the vehicle. We had several experiments to reach the end of the construction. We gave our own car some special designs; therefore it would look nice and creative.
At last, there were seven mousetrap cars designed and experimented by seven physics club members. Each of us had a various design. Mr. Gurkan Cil, who searched and prepared the mousetrap car project, eventually arranged a fabulous mousetrap race, which took place on 23rd January 2007 with all the physics club members participated. Racing field was decided to be in ZIS, Kindergarten and Primary Department, where the floor is smooth (less friction). Each candidate and their experimental mousetrap cars were numerated from one to seven.
As well as students and teachers, Mr Osman Karaca, the principle of ZIS, was present at the race as spectator. Some of our friends were cheering and supporting the candidates that made us felt as if it had been a real car race, unlike the experimental races we had done before it was quite fun after all.
The race started after each car was ready, car axle was winded up with string connected to the lever arm with the other side. The cars raced one by one, one after another starting from number one to number seven. The longest distance taken by the cars was measured to be 25 meters. The winner was Monika Lavan (11F), second Lida Eang (11F), third Ny Srey Kam (11E), followed by Molika Pich Prak (11E), Vuthyka Men (11E), Sroy Kim Chuo (10E) and Sethikdanique Oum Hem (10E). The car built by Molika Pich Prak (11E) was selected for the best design. All of the competitors were awarded with some gifts and was provided with a certificate of attendance for the mousetrap race. There was a surprise gift for the winner, and the gift was opened immediately after the race. The gift was two little white mice. We raced together and we enjoyed together. It was a wonderful achievement for completing our first term project "Mousetrap Car". The physics club members would like to thank to Mr. Gurkan Cil for the amazing project he had provided and the encouragement he increased.
You should try to build a mousetrap car, it is fun and amazing, or try with your friends then you can arrange a race among yourselves. If your question is "where to begin?" there is no "only one" way to build a mousetrap powered vehicle, the best approach is to apply you best understanding of the laws of physics without over exaggerating any one concept. As a designer, one should understand the concepts such as velocity, friction, energy, power, simple machines, Newton's laws, inertia and rotational dynamics, so as to help them in building the car. Try to find a harmonious balance between all elements and variable in order to achieve the best results. Do not suppose that there is only one style of vehicle to build for success. We have built cars using many different approaches and all vehicles are record setting contenders.
There are some helpful hints for better performance of mousetrap car such as to reduce friction because most friction between the materials in the car reduces the amount of energy that is used to move the car. If the mousetrap is located close the drive axle the wheels can spin at the start so it will waste energy. If the mouse trap is located too far from the drive axle, there will not be enough pulling force to propel the racer to the finish. It is important to try the mouse trap in several locations from the drive axle in order to find your car's best performance. If you want to improve your mousetrap vehicle, you should experiment and report your car upon changes. You can try changing position, materials or technique of the system and compare the result if it is better or worse. Try to encourage creativity. For example, the car does not have to have four wheels. Three and two wheel models will work very well if designed properly. Lids, compact disks, records, butter tub lids can be used as the wheels. Let's see how good you are at building a simple machine mousetrap car.
You can look up more information through internet or visit the photos section of the website to view the photos of our experiments. Have fun with this incredible project of mousetrap car. All the club members had done well with the project and ready to share experience with those who are interested.
Prepared by Monika Lavan & Lida Eang
How to Build a Mousetrap Car (PDF File)
Mousetrap Car Race 2007 Video