Unit 2: Electric Car
Step 1: Problem Situation
Model Race Car Design & Construction Instructions
Each student will design and create a model electric car that includes a series circuit with the following parts:
- “AA” Battery holder [with 2 AA batteries]
- One ‘block’ of pine wood ¾ x 3 1/2 x 8
The car will utilize 4 wheels, 2 wheels of corresponding size for the front wheels and 2 wheels of corresponding size for the rear wheels. These wheels will be ‘joined’ with axles. Students will be given a pack of gears that they shall utilize in the planning of their vehicle as so the vehicle doesn’t have too much torque and spin out. These gears will be used in combinations to reduce the speed of the car.
Push Button Switch
'AA' Battery Holder (holds 2 batteries)
(Front and Back)
Pulleys (3/8, 6/8, 9/8, 12/8)
Gears (12t, 20t, 30t, 40t)
Wood for Base and side rails
Hot Glue Gun
Saw (Band Saw or Coping Saw)
Step 2: Research and Investigate
Students will read pages 180-199 from the textbook Gateway to Engineering about Energy. A discussion on Work, Power , the Law of Conservation of Energy , Potential Energy , and Kinetic Energy will take place. (Please explain the information that was researched in your communication to the class. You should include the definitions to the terms above and be able to explain gear ratios and drive systems).
In your Design Portfolio, describe two possible solutions that your team has created for the problem. (Please indicate with a sketch or drawing the different ideas that you came up with to solve the problem in step #1. These drawing MUST be annotated [meaning have word descriptions explaining the drawing] and NEAT).
Students will need to create Thumbnail Sketches of different ideas that they have for their 'Electric Car'. These should be drawn in each students’ Design Portfolio. Alternative designs must be compared. Designers must choose the one that works best, is the most economical, and has minimal negative impact on people and the environment. When technologists design, they consider principles such as functionality, quality, ergonomics, safety, aesthetics, and maintainability.
Students thus will need to select which drawing they will create as working sketch. Please remember to include the following parts: motor, batteries, battery holder, gears, wheels & axles, frame. The wood block that is used to create the frame is 3/4" thick x 3 1/2: wide x 8" long. It can be cut any way that you would like to create the frame. Remember that where you put your components has a great deal to do with how well your 'Electric Car' will work.
As we learn about the different parts of the electric car we will compare the actual results with our first ideas.
Copy the following table into a Microsoft Word document and save to your "H" drive @ BSMS. Fill in the table. Your teacher will check your work electronically.
Task that needs to be completed. State the Design Challenge in your own words:
Materials Available for Use:
Electric Car weight:
Size of drive wheels (diameter):
Circumference of drive wheel:
Gear ratio selected:
Estimated (mathematically) distance car will travel in 20 seconds with 'no load':
Motor Rpm _____ x Gear Ratio___:___ x circumference of drive wheel _____/3 (20 seconds)= estimated distance traveled __________.
Explanation of Design that was chosen (why this design?):
Why we chose this design ______________________________________________
Step 4: Choose and Justify the Optimal Solution
Refer to your Design Portfolio. Explain why you selected the solution that you did, and why it was the better choice. (Must have a written reason for why you chose the design. May NOT use 'because I liked it better' or similar response). This is where you should include the information that explains what gears, pulleys or combinations of gears and pulleys you used in your project.
1) Does your project use gears [only]? If yes, which ones?
2) Does your project use pulleys [only]? If yes, which ones?
3) Does your project use a combination of gears and pulleys? If yes, which ones?
4) How fast will your electric car go? SHOW ALL MATH!
Step 5: Develop Your Prototype
Solder together your series circuits. It is important to remember the following when using a soldering iron:
The iron is hot. You can get burned!
Solder is a solid metal when at room temperature. When it is heated up it melts (like hot glue from a hot glue gun).
The solder flows to the heat...therefore heat the component that needs to be attached.
Keep the soldering iron in its holder when not in use. This will prevent people and items from getting burned.
The amount of gears and completed body design play a very important part in your vehicles grade. (Remember to explain HOW you made your vehicle!)
Series When the components are connected one after another the circuit is called a series circuit. In a series circuit there is only one pathway for the electrons to flow. A break in any part of the circuit stops all the electrons from flowing. Two rules apply to series circuits: 1) The current is the same at all points; 2) The total resistance of the circuit is equal to the sum of the individual resistance values.
Explain how your series circuit makes your electric car work.
Step 6: Testing and Evaluation & Step 7: Redesigning
How will you test and evaluate your design? In your Design Portfolio, describe the testing procedure that you will use.
(Explain how the results show that the design solves the problem and meets the specifications and constraints. If your vehicle did not work correctly THE FIRST ATTEMPT you probably needed to redesign a part or parts. Please include the problem that arose and the solutions that you used to correct the problem.)
Testing of Materials. Go to www.phschool.com and type in the following web code gal-0307 to learn about impact testing materials online.
Step 8: Communicate Your Achievements
In your Design Portfolio describe the plan you will use to present your design to your class. Show what handouts and/or PowerPoint slides you will use.
Setting the Scene Can You Picture It?
Saying that "a picture is worth a thousand words" is especially true in technology. At each stage of design, architects, engineers, and all types of designers use pictures to communicate ideas.
- Sketches and simple drawings are used during the early stages of design. They help clarify the problem, and they are used to brainstorm ideas with other people.
- During the later stages of design, more detailed technical drawings are used to present a variety of ideas and solutions. These drawings may use color and texture.
- Three-dimensional models are often used to show the final design idea. They can range from simple cardboard reproductions to a computer simulation.
- Many design ideas are also illustrated using tables, graphs and charts.
Effective Presentations With Visual Aids
A good presentation is an important part of the design process. Often, presentations are made to convince clients that a design is worth producing. They are also made to market the product to potential customers. Without the support and enthusiasm of these people, the design would remain a good idea instead of being developed into a successful product.
YouTube Video: Revenge of the Electric Car