Physics Final with Home-made Car

What does it look like, how was it built, and what materials were used during the construction?

The car has an overall box-like shape. During construction, aerodynamics was not considered because the car would only be traveling at a very low velocity. Balsa and ply wood were the two main materials used. The body, consisting of balsa wood, is long and narrow. Our car, most noticeably, is silver. We used spray paint to color the car, just to make it look cool. It has four wheels, two on the front and two on the back. The car measures about 7 inches in length, 3 inches in width, and ¾ inch in height. The wheels are 1 ¾ inch in diameter and about 6 inches in circumference. The axels are about 3 inches long and about 3/8 of and inch wide. Also…our rubber band is green!

In building our car, we first used a coping saw to cut out a rectangle in the middle of our already rectangular 7 x 3 inch balsa wood. We then used a hole-saw to cut out our four wheels. Two of the wheels, those used in the rear (or our driving wheels), are made of plywood, and the front two are made out of balsa wood (there is no reason for this change in wood other than we ran out of balsa wood).

Energy is created by the stretched rubber band when it is released. The spring caused by the unwinding rubber band exerts a force on the back wheels through the nail attached to the wooden concave piece. As the band unwinds around the concave piece, it is traveling through a distance so Fd = W (work). The elastic potential energy comes from the rubber band as work depends on how many times you wrap the rubber band around the nail (or axel).

At all points along the car’s path, the gravitational potential energy is the same. They are all the same distance off the ground level. Shown in calculations, this number is 3.065 joules. At the beginning point of the car’s path, there exists potential energy due to the stored energy in the stretched rubber band around the drive wheels (or back wheels). There is no kinetic energy yet because the car is stationary. As soon as the car is released, the quickly unwinding rubber band immediately converts its gathered PE into KE, forcing the car forward. When the rubber band is completely unwound and the car has reached its highest acceleration point, all the PE has been converted into KE. From this point on, the KE will expend itself due to the friction between the axels and wheels and the wheels and traveling surface.

The actual range of the car was 1.26m. Some sources of error may be that with each of the trials, the number of times the rubber band is wound may be slightly different, and friction may decrease the speed of the tires.

Some topics in this essay:
Lauren Terminator…, Fd Torque, KE PE, rubber band, KE KE, PE KE, concave piece, potential energy, balsa wood, car’s path, kinetic energy, wooden concave, band stretched, wooden concave piece, stretched rubber band, final velocity, stretched rubber, band band stretched, energy car moving, converted kinetic energy,