Physics Mousetrap Car

Newtons laws were very applicable to the cars performance. The first law told us that the car wouldn't stop unless there was an external force acted upon it. The only external force that would act on our car would be the force of friction. This told us that we wanted to have  surface or wheels that would have as little friction as possible. Friction was our enemy within this project. The second law told us that we want to make the object as small as we could because we wanted the quickest acceleration. To get a high acceleration you want to maximize force and decrease mass. Our force was constant so the smaller the car the better. The third law told us that each reaction had an equal and opposite. This means that as the car moves friction will cause it to slow down. Also as the string pulls the axle to axle pulls the string equally but since the car has a small mass the force is able to cause it to move. This means the force of the mousetrap is greater than the force of friction. The part of the car that we wanted to have friction was the part where the axle touched the wheels. This was helpful because if there isn't friction on the axle will turn without the wheels, and we want to maximize their rotations. On the other hand friction on the wheels was bad because the more friction the ground would push the car back. You also do not want friction on your axle to string. This is why we added a balloon on our axle to reduce friction between it and the string. Our wheels began too small; they had little rotational inertia but couldn't gain very much tangential velocity as disks could. This is why we switched to get bigger disks. The disks were not too hard to get a torque but they were also able to get a great tangential velocity. The car's only force was the force of friction as it moved and the force of the trap. The trap is what made the car go forward and it had the same amount of energy as it went. But as the car went forward friction would slow it down until it completely stopped the car. The potential energy is stored in the spring and then when you let it go it is converted into kinetic energy. We can't calculate the work of the spring because the spring's direction is not parallel to the direction which the car is moving.

Reflection-
My final design changed a great deal. For one, the wheels had to adjust to become disks because our original disks were too small. Also we added a balloon on the axle to increase the friction between the string and axle. We also added tape to the wheels to decrease friction between the ground and wheels. We also used yarn rather than string because it was much stronger and sturdier. One of our problems was winding the yarn because sometimes the wheel with the axle was our front wheel and we wanted it to be our back wheel. We also had to use several pieces of yarn because they kept getting tangled causing the yarn to stop half way through the run. If I could do the project again, I would have started earlier. I would've finished it sooner so I wouldn't have had to adjust after it was too late. If I were doing another building project, I would work in a group of three because the work is then divided into smaller parts. Also I'd add someone who has past experience in the subject because neither of us knew what we were doing.