Project Description:

Overview:

In this project, students design and build a vehicle powered by a rubber band and propeller. The car will be evaluated on its efficiency (distance per turn of the propeller).

Specifics:

• Explain the following requirements to the class:
  

1. The car must use a propeller as its sole source of propulsion.
   
2. The propeller must be rubber band powered.
   
3. No commercially made materials may be used (i.e. propellers, wheels, etc...)
   
   

• Explain the testing procedure. The car will be tested on its efficiency.
  

1. Wind the propeller 25 times.
   
2. Place the car on a starting line and release the propeller. Measure the distance the car travels.
   
3. Repeat this process winding the propeller 50 times, 75 times, and 100 times.
   
4. Average the distances traveled in the four trials. This average is divided by 62.5 (the average number of propeller turns in the 4 trials). This number is the efficiency (distance/turn).
   
   

The objective of this project is to expose students to concepts of forces, friction, and Newton's laws of motion.

Timeline:

This project can be completed as an in class or out of class project. If it is done as an in class project expect 13-15 days. As an out of class project, allow the students 4-6 weeks to construct and test their cars on their own. Two days will be needed to test the devices. A practice/workshop day is highly recommended halfway through the project.

Materials:

Construction Materials: The students should supply materials if this project is completed out of class. (See Helpful Hints for a guide on how to build a propeller car.) The materials used should be very light weight. None of the materials may be commercial products. Some materials they may wish to use are the following:

• Body- paper tube, balsa wood stick, dowel rod
  
• Axles-wire, plastic dowel rods, ice cream push up axles
  
• Wheels-notecards or file folders, construction paper, cardboard, compact disks
  
• Propeller-notecards, file folders, thin plastic (milk jug), wire for shaft
  
• Motor-rubber bands (A limit on the size and number of rubber bands may be used to keep this standard.)
  
• Additional materials-Straws for the axle and propeller shafts, paper clips for motor hooks
  
  

• Tape for a starting line
  
• Meter stick for measuring the distance traveled
  
  

The assessment of this project will be based on three items:

1. Quality and originality of design-A small portion of the student's grade should be based on the overall quality of the finished propeller car. This will reward students who invest more time in planning, drawing, and building the project.
   
   
2. Performance Score-Each student's vehicle will be tested and scored according to the efficiency. The efficiency of the car measures the average distance traveled per propeller turn. The following formula should be used to calculate efficiency:
   E=average distance traveled/average # of propeller turns.
   (See Project Description for detailed testing procedure.) Rank the students based on this efficiency.
   
   
3. The paper-Each student's paper should be graded based on the the explanation of the car and how the car works. Specific questions about the science behind the car should be included in the paper. (Sample paper template.)

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