Building the Rubber Band Car for MTV Project

The sketch of the rubber band car:

Material:
Body - Plastic basket

Axles - 2 dowels

one rubber band

4 wheels

a hairpin

Steps

-  Put the dowel through the basket as the axis of the car.

-  Fixed two sides of the dowels with the wheels, make sure it tight, not fell out.

- Tie the rubber band in one dowel.

- Using the hairpin to hold the rubber band in other fixed surface area of the basket 

- Turn the axle to wind the rubber band

- Set the car in smooth hard surface and let it go. 

 -After the first race, the car did not went over 2 meters, the rubber band hold the car to stop to continue going when the spins of the rubber band end, the rubber band at first stay at the end of the basket overstretch.

- The sencond time, another end of the rubber band put in the fixed surface very close with the end tied on the dowel, the rubber band, release, snapped back to its original form very quickly.

- The rubber band at the middle of the basket, the rubber band not overstretch, can spin more rounds, the car go farther.
-

Analyze 
The car carry a kilogram mass went 2 meters for 4 seconds 
The speed of the car is 0.5m/s
For the first second, the car moving slow and accelerate on the 2 seconds.

       The car did not go as far as its morden design car, the morden car using the longer rubber band, the rubber band spinning process longer, more kinetic energy create. Before moving, the car has no kinetic energy, when the rubber band twisted tight, it had the potential energy.
        The wheel has large affect on the car, the bigger the wheels are , the longer distance the car can travel.
The bigger more surface area touched with the ground than the small wheel; also if using the C.D as wheels, it hard for going in the straight line, it nescessary a certain roughness on the wheel to go straight and faster.
         While carry a kilogram mass, the speed of the car slow down, more friction involved.
          The car going backward after the spinning process finished.
Conclution
          Physics concept :
- Energy can be stored by twisting a rubber band called potential energy
- Energy the car had while moving called kinetic energy.
- If something starts to moving without a force pushing on it, it means energy being used.
- The heavier object has bigger friction.
          Formular:
       Speed = Distance/times
Learned to applied physics concepts to design a project, observed how a system work, and being creative.