1. Summary & Printable Handouts

Electric Motorboat Drag Racing is a culminating high school physics project to apply and bring to
life the California Content Standards for Physics. Students design, build, and race model-sized electric motorboats.

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Further Investigations:

• Which battery(ies) provides the best performance?
• Which motor provides the best performance?
• Which hull design provides the best performance?
• Which propeller provides the best performance?
• Which propeller angle and shaft length provides the best performance?
• Which material and/or coating provides the best performance?
• Which selections are the most cost effective?

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2. Selected California Physics Standards

The project gives students hands-on experience with these CA Content Standards for Physics:

• 1b. Students know that when forces are balanced, no acceleration occurs; thus an object
  continues to move at a constant speed or stays at rest (Newton’s first law). “A push or a pull (force) needs to be applied to make an object accelerate.”
   

• 5a. Students know how to predict the voltage or current in simple direct current (DC) electric circuits constructed from batteries, wires, resistors, and capacitors.
   

• I&E 1c. Identify possible reasons for inconsistent results, such as sources of error or uncontrolled conditions.

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3. Evidence for Attainment of Standards

The student demonstrates his or her attainment of the standards in the following ways.

For 1b:

• Student designs his boat to have an unbalanced force accelerate it forward from rest.

• Student increases the forward force from the motor by improving its angle or battery power.

• Student decreases the resistance forces of friction on or within the boat.

• Student reduces the mass of the boat to increase its acceleration from the same net force.

• Student accurately completes page 1 of the Physics Worksheet.

For 5a:

• Student designs his boat to have a properly wired circuit that he can turn on and off.

• Student increases the motor's force by using fresh, more or higher voltage batteries.

• Student fixes a dead motor or malfunctioning circuit by checking and fixing wire connections.

• Student accurately completes page 2 of the Physics Worksheet.

For I&E 1c:

• Student notices inconsistent boat performance and communicates the causes or reasons.

• Student adjusts or changes the boat design, shape, or materials to improve or fix it.

• Student adjusts or changes the boat's batteries, wires, or motor to improve or fix it.

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4. Materials Needed: Rain Gutters, Water & Stopwatches

For about $40, four 3-meter plastic rain gutters (at least 9cm wide or notify your students), two connectors, and four end caps (seen in starting photo and video clip) can be purchased from a local home improvement store (find a local store here). Typical rain gutters are 3 meters long, so they need to be connected in pairs to make both drag racing lanes. The four rain gutters will require about 20 gallons to fill, so 5-gallon jugs, buckets, or a hose are recommended for use throughout the competition. Three stopwatches are also recommended to time the races.

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5. Project Timeline

The project can be assigned during 1 class period using this website and discussion (and the Project Rules printout). No other class time needs to be given for working on the project. Students should be given approximately 6 weeks to complete the project at home. It is important students begin looking for materials right away, especially propellers. One day after school can be planned for boats to be tested. Once the boats are due, the actual boat inspections, qualifying, and drag racing tournament will take 2 class periods (use the Grade Sheet and Tournament Tree). You may also use an additional 1 to 2 class periods to complete the Physics Worksheet.

If you have multiple classes, plan for a final tournament with the fastest boats. The final tournament is a great opportunity to invite the school newspaper, yearbook, and community newspaper. Have awards, a perpetual plaque, and/or give extra credit to the fastest boats in the final tournament.

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6. Rain Gutter Setup

Using a permanent marker, mark lines that are one-half meter from each end of both drag racing lanes (see starting photo). This allows for a visible starting and finishing line, 5 meters apart, and start and stop zones without anything to interfere with or damage the boats.

The rain gutters should be setup side by side about a fifth of a meter apart on level concrete, such as a level sidewalk (see video clip). A typical drag racing lane (two 3-meter rain gutters) requires about 10 gallons to fill, so use 5-gallon jugs, buckets, or a hose to fill and re-fill them during the races as necessary. To level the lanes and water, you can insert folded newspaper or thin boards under the middle of each sagging section (in video clip).  Fill lanes uniformly to the top (see photo).

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7. Officiating the Tournament

Before the tournament (class): 1) print the Grade Sheet and Tournament Tree, 2) setup the rain gutters and have water available to re-fill them, 3) get stopwatches and students to help time the boats. The teacher should time the winning boats and assure they are placed accurately in the tournament tree.

First, the boats must be inspected and attempt the distance to earn a grade. Use the Grade Sheet to check & record a score for the following information: 1) student names written on or attached to the boat, 2) proper materials (no manufactured toy boat body), 3) boat size (length<35cm and width<9cm), 4) proper batteries (one 9V or up to six D, C, AA, or AAA), 5) only one or more electric motors to power the boat, 6) the number of meters the boat propelled itself at one time, and 7) the time the boat needed to complete the 5 meter distance. The boat must meet all of the rules and propel itself the complete 5 meters at one time to qualify for competition.

Second, start the competition, but not the tournament. Students pair up and the teacher starts the race with "Ready, Set, Go". The teacher times the race from "Go" to the moment the finish line is broken by the winning boat. The teacher records the times for the boats on the Grade Sheet. Enforce fair-racing practices and allow a re-start if one boat did not start or started too early. Allow every qualified boat to race at least once. Keep track of the fastest eight boats and let students know what time or boat they have to beat to be in the fastest eight. Once you have the fastest eight boats, you are ready to start the class tournament.

Third, use the Tournament Tree to pair up the fastest eight boats (1st vs. 8th, 2nd vs. 7th, 3rd vs. 6th, and 4th vs. 5th).   If a boat breaks and cannot continue in time, you may give its opponent a win or replace it with the fastest available boat. Once you have the fastest four boats, pair them up (1st vs. 4th, 2nd vs. 3rd) based on their current winning times. Have the two losing boats compete in the drag race for 3rd and 4th place and the two winning boats compete in the drag race for 1st and 2nd place in the class. Time permitting, announce and make these final matches the best two out of three to win.

If you have multiple classes, choose the fastest eight and arrange for a final tournament. The final tournament is a great opportunity to invite the school newspaper, yearbook, and community newspaper. Have awards, a perpetual plaque, and/or give extra credit to the groups with the fastest boats in the final tournament.

Email rbarry@electricboatproject.com feedback, questions, comments, pictures and times!

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