Rubber Band Cars
Cars that are powered by a rubber band using a select amount of materials.
Materials
Two CDs, One Skewer (allowed to use more than one), one rubber band, duct tape, and one cardboard cutout.
How We Made Our Cars
We made our cars by using two skewers, one of the skewers we put through a cardboard with a square cutout in it. We then attached CD's to act as wheels on both sides of the skewer sticking out of the cardboard. We then taped the CDs to the skewer and balanced the CD on the skewer for the best performance in terms of distance. After, we attach an elastic onto another skewer. To make the car go forwards you wind the elastic onto the skewer, then release and the car will move.
Kinetic Energy: Kinetic energy is the energy of motion of an object.
Elastic Energy: Elastic energy occurs when objects are compressed, stretched, or deformed in any way.
First, potential energy is made when you put force towards an object. So that means, elastic potential energy is turned into kinetic energy when you put force into an elastic. For example, as you stretch an elastic, elastic potential energy increases, and as you let go of the elastic kinetic energy increases.
Important modifications
The first adjustment that improved the car, was putting rolls of tape the size of the hole in the CD's wheels and on the skewer axles in order to keep the wheels in place. This kept the wheels from touching the base, and kept them from becoming crooked. This model went around 25 feet.
Another adjustment to the car that worked well and improved the car is, attaching a rubber band to the skewer to stretch the rubber band farther. By stretching the rubber band farther, the car had more speed, and more power. This also gave the car a distance around 30 feet.
Our group also put a long skewer into the back of our car to keep the back of our car from touching the ground too much, and slowing down. By doing this, our car didn't drag as hard against the ground. This made the model go 38 feet.
Lastly, by removing the previously added rubber band wheels, we improved the distance of the car greatly. Before, rubber bands were applied to the wheels to create traction, but apparently the wheels gripped the ground too well. When the rubber bands were removed, our car moved way faster and went to an improved distance of 50 feet.
In the end, our greatest distance was 50 feet.
Video Physics
I used the Video Phyiscs app by taking a video of the rubber band car going across the room. In the background there was a meter stick, so when you finish recording you can scan the meter stick and set the distance of the car by one meter. During the video you manually place dots on the screen where the rubber band car was so the app can calculate the velocity and acceleration of the car.
Formulas: The formula for acceleration is the change in velocity over the change in time.
Formula: The next formula is the first point of velocity minus the second point of velocity over the first point of time minus the second point of time.
In this picture, to calculate velocity you need to pick two points. Once you pick the two points you find the difference in velocity for the first point and the second points. Then after you find the difference in time for the first and second points. Once you solve that equation you can get your acceleration.
Answer: .21m/s squared