1. Rubber Band Powered Cars

Your Mission: Inquiry, Design, Iteration!

1. Conceptualize & Sketch: Begin by exploring possible designs. How will the elastic potential energy of the rubber band be converted into kinetic energy for your car? What structural forms will provide the most efficient transfer of this energy? Consider different wheel-to-axle connections and how they might impact motion. Document your initial thoughts and sketches; these will be your blueprints.

2. Strategic Material Use: Gather your chosen materials. Before you cut or assemble, consider the properties of each material. How can cardboard provide structural integrity? What role will pencils play beyond just axles? How can the CDs be optimized for traction and smooth rolling?

3. From Concept to Prototype: Now, translate your design into a physical model.

   • Frame Stability: How will you construct a robust and lightweight frame that provides a stable foundation for your car’s components?

   • Axle Integration: What is the most effective method for securing your axles to the frame, ensuring minimal friction while allowing for free rotation? How will the straws facilitate this?

   • Wheel Dynamics: How will you firmly attach the CDs to the axles? What strategies can you employ to ensure the wheels achieve optimal grip on the testing surface and roll smoothly?

   • Propulsion Mechanism: This is the core of your design. How will you configure the rubber band(s) to store and release energy most effectively? What mechanical advantage can you create to maximize the force applied to the wheels? Will a direct drive, a lever, or another mechanism best suit your design?

   • As you build, continuously evaluate: “Does this component contribute to our goal of maximizing distance?”

4. Test & Analyze: Set up your testing environment with a clear, flat surface and a distinct start line. Release your car and observe its performance. Precisely measure the total distance traveled.

5. Reflect & Refine:

   • Analyze your initial test results. What forces were at play? Where might energy have been lost?

   • Based on your observations, what specific modifications could enhance your car’s performance? Consider variables such as wheel diameter, mass distribution, number and tension of rubber bands, and the reduction of friction.

   • Implement your improvements and re-test. The iterative cycle of design, build, test, and refine is fundamental to engineering innovation.

Rules for Success:

To ensure a fair and insightful challenge, adhere to these guidelines:

1. You must build a vehicle with a frame, at least one axle, and at least one wheel.

2. The car must be a single device. No parts of the car can intentionally or unintentionally detach, fall off, or otherwise separate during the test.

3. The car must be powered entirely by one or more rubber bands. No other sources of forward force or movement, such as pushing or blowing on the car, are allowed.

4. All rubber bands that power the car must be pulled/twisted/tightened, etc. by hand by up to two people. No additional external tools or sources of leverage that are not part of the car (wrenches, power drills, etc.) are allowed to help tighten the rubber band.

5. The test must be conducted on a flat surface. Any surface (carpet, wood, concrete, etc.) is acceptable.

6. A straight start line must be marked on the floor, using any material that will not create a bump or impede the car’s motion (tape, chalk, etc.). The car must start completely behind the start line.

7. After the car has been released, no one can touch the car, and it cannot touch or bump into any objects, until it comes to a complete stop on its own.

8. After the car has come to a complete stop, distance is measured from the point on the start line directly in front of where the car started to the closest point on the car.