Rubber Band Cars By: owen DUggan

- BASICS -

For the past couple weeks we have been working on elastic band cars trying to make them go farther each day. This cars consist of the following materials: cardboard, rubber bands (varying in length), thin wood sticks, duck tape, and discs.

How are they made?

The first part to making are cars was cutting 2in by 1.5in insert in the front in the cardboard. Then, we would take a thin wooden stick, and insert into the cardboard. From there we would rap tape around the sticks, so that the disc could stay on. Once we put the disc on we would take an elastic band, and tape it onto the back of the car. This was the first model of car, but we later went on make modifications.

How do they move?

To make the care move you would have to take the rubber band and wind it up around a stick. By rapping it more and more we are giving it more potential energy. Once the rubber band is released this potential energy turns into kenotic energy. This drives the car to move forward with the wheels turning.

Potential energy - the energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors

Kenotic energy - energy that a body possesses by virtue of being in motion

Modification 1

Our first modification involved our wheels. We tried to surround the disc with duck tape, so that we could get a further distance. This car went about 13 feet

Modification 2

This second modification allowed are car to move more smoothly. By cutting of the back, and adding 2 sticks we were able to reduce the friction. This care went 15 feet.

Modification 3

This third modification was one that many people used. I would like to take credit for being the first one to think of this. The rubber bands on this car helped the car grip the ground better similar to our first modification. This car went 24 feet.

Modification 4

This modification was basically two in one. We decided that instead of using two stick we would use one. We would then tape the elastic band on, but it was cut. By setting it farther back the car could have more potential energy. This car went about 47 feet.

By using the Video Physics app we were able to track the speed in which are car went (velocity). We could also see the acceleration be viewing the graphs made by tracking the car. We were able to do this because we took a video of our car, and then went on to track the car with little dots. This dots help the computer indicate where our car was and at what times. This allowed us to track the velocity and acceleration.

The reason the camera is set so far back is because we need to be able to view the distance of the car. If we had not taped it from the side we would not have been able to track the car. This is because we had to line up the dots with the center of the wheel, and without making the camera facing that way it would not be possible.

We can calculate the velocity with this first graph because it gives us the distance and the time. The second graph then shows the velocity(meter per second). It did this by dividing the distance by time. The acceleration of our car was .375m/s squared. I found this out by taking two points on the graph, and taking there times and velocity. Then I would plug them into the equation a= Vf-Vi/ Tf-Ti

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