Prior Car's Problems and Improvements (Main Post Highlighting Physics Principles)

Problems
Our previous car was filled with many problems.
1. The wheel was in contact with the dowel. This created a lot of friction due to the roughness of the cardboard rolling against the dowel.
2.Large washers were glued around the sides of the wheels. Eventually, the wheels wore down causing the large washers to touch the ground. This caused bumps and uneven rotation of the wheels.
3. The entire body of the car proved to be very unstable when Akul rode the car. The cardboard was not sturdy and it wobbled a lot. In addition the car was mostly just a dowel and it looked very slim and like as stick

Improvements
1. After recalculating, we learned that mass does not matter. Potential energy gets converted into kinetic energy and friction. The equation would be mgh=1/2mv^2+uFn, where F normal would be equal to mgcostheta so the equation would be mgh=1/2mv^2+umgcostheta. The masses cancel out so we can see that mass is not taken into account during calculations. From this, we did not put effort into adding more mass to the car, as it did not matter. Therefore we removed washers from the wheel.
2. The body of the car was made slim in order to reduce the air resistance.
3. (Main Improvement) An improve system of rotation for the wheels was implemented. Using the same wheels, small pieces of pvc were cut and put into the holes of the wheels. The holes were very tight, enough to hold the PVC in place. This was done for each of the wheels. Two dowels, one in the front and one in the back were secured through holes in the cardboard. The PVC in the wheels would have the dowel inside of them so that they would roll freely. So essentially the PVC and the wheel would be rolling against the stationary dowel which reduces friction because the surface of the contacts when rotating belong to the smooth pvc and smooth dowel. Also washers between the cardboard body and the pvc prevented contact with the cardboard and allowed smooth rotation against the the washer instead of the cardboard This reduced friction.
4. To improve stability, we layered three strong banana boxes as the seat and main body of the car. In addition, glue and strings helped tie and keep the car in place.
5. Steering system was improved by extending the handle for the feet to push on. This increases the torque because the lever arm is increased. Torque is equal to force times lever arm. So force is torque divided by lever arm. This means more lever arm will have less force required to steer so the driver can steer more easily.
6. The overall design of the car looks a lot better. More decorations were added and the car now better resembled a real car. In addition, the car was larger now and more comfortable to sit in.
7. Keep the small front wheels because the radius is small which makes it have less rotational inertia which means it spins more easily. The back wheels need to be large to support the car and so that they can reach the ground.