Grade Level and Course:  6th Grade Science

Title:  Need for Speed

Topic:  Laws of Force, Motion, and Energy in Racing

Summary of lesson:  In this lesson, students will design a model race car and use their model to investigate the relationship between the potential and kinetic energy of their model as it travels down a ramp.  Students will also investigate how the acceleration of their model is affected by forces applied and the mass of their model.  Students will be asked to identify variables that may affect the acceleration of their model and then design an investigation to test design modifications to reduce friction and air resistance.  Students will collect data during their investigation and represent their data in graphs so that they can compare their data with that of their classmates.  Students will communicate the results of their investigation and justify their final design choice based on the data they obtain in their investigation.  

Concepts:  

• effects of forces on motion of objects
• relationship between force and mass and acceleration
• relationship between potential and kinetic energy
• effects of mass and height on gravitational potential energy
• modifying a design based on data obtained in scientific investigation
• applying experimental design
• collecting and analyzing data
• communicating results from scientific investigation

Objectives:  Following this lesson, students will be able to:

• Design an investigation to test variables that affect the motion of their model race car.
• Modify the design of their race car based on data obtained in scientific inquiry.
• Present their design to the class, describing why the final design was selected and justifying the design with data obtained in their investigation.
• Present their data clearly and correctly in appropriate graphs/charts.
• Explain the relationship between potential and kinetic energy.
• Explain the relationship between force, mass, and acceleration.
• Explain gravitational potential energy and calculate the GPE of their model race car.
• Design a race car that minimizes the force of friction and maximizes acceleration.

Background for teachers:  

This lesson is based on the concept of a real-world engineering competition hosted by the Progressive Insurance Company.  Details of the competition can be found at:  http://www.progressiveautoxprize.org/prize-details.  A short summary of the competition follows:
"The Progressive Insurance Automotive X PRIZE was a global competition that awarded $10 million to three teams that built cars that achieved at least 100 MPGe in real world driving. These cars were safe, affordable and desirable with the ultimate goal of offering more efficient vehicle choices to consumers.With our partners at Consumer Reports, we also advanced the adoption of a new consumer metric, called MPGe (Miles per Gallon or gasoline equivalent energy), that offers consumers the ability to make an apples-to-apples comparison of this next generation of vehicles that will use a variety of energy sources and fuels with the conventional cars they drive today.
Progressive Insurance was our Title Sponsor and the U.S. Department Of Energy our major supporter because they believe in incentivizing innovation through competition to reshape the automotive industry.It was truly a public/private partnership.”

• Mainstream class entries were required to seat at least four passengers, have four wheels, and have a minimum 200 mile range
• Alternative class entries opened up the design space a bit by reducing the requirements to seat at least two passengers with a minimum 100 mile range and no minimum on the number of wheels
• Regardless, to win, vehicles must have completed all on-track tests, demonstrated fuel economy numbers equal to at least 100 MPGe, passed all FMVSS requirements, and completed validation testing on the chassis dynamometer.
• Beyond these, the fastest time clocked in the Finals Events won

In this lesson, students are going to have the opportunity to apply what they have learned about experimental design to develop a model race car that will minimize the effects of friction and air resistance.  Students can then use their models to investigate and demonstrate several scientific concepts related to forces, motion and energy.  Automotive designers must take into consideration how their designs will perform in a variety of conditions.  Obviously, race car designers have speed as one of their top priorities, but they still must take into consideration safety and budget constraints as they develop their design.  Automobiles that are produced for the general public have many design parameters that must be met, but one of the most significant ones for automakers, and buyers, in our current economy may be those related to fuel efficiency.  

There is an interesting article online about a concept car from Volkswagon that was able to achieve 285 MPG.  (http://gas2.org/2008/03/12/the-worlds-most-fuel-efficient-car-285-mpg-not-a-hybrid/)  

Another article worth viewing from the engineering perspective can be found at http://www.engineerlive.com/Asia-Pacific-Engineer/Automotive-Design/Improve_fuel_efficiency_and_cut_automotive_emissions/21767/

The model race cars in this lesson will be fueled by nothing other than the gravitational potential energy of the car.  Gravitational potential energy (GPE) can be calculated using the following formula:
GPE = (Height from ground) * (acceleration of gravity = 9.81 m/s/s) * (mass of object)
An excellent explanation of gravitational potential energy and the relationship between potential and kinetic energy can be found at http://en.wikipedia.org/wiki/Potential_energy#Gravitational_potential_energy


“Gravitational energy is the potential energy associated with gravitational force, as work is required to elevate objects against Earth's gravity. The potential energy due to elevated positions is called gravitational potential energy, and is evidenced by water in an elevated reservoir or kept behind a dam. If an object falls from one point to another point inside a gravitational field, the force of gravity will do positive work on the object, and the gravitational potential energy will decrease by the same amount.

Consider a book placed on top of a table. As the book is raised from the floor, to the table, some external force works against the gravitational force. If the book falls back to the floor, the "falling" energy the book receives is provided by the gravitational force. Thus, if the book falls off the table, this potential energy goes to accelerate the mass of the book and is converted into kinetic energy. When the book hits the floor this kinetic energy is converted into heat and sound by the impact.

The factors that affect an object's gravitational potential energy are its height relative to some reference point, its mass, and the strength of the gravitational field it is in. Thus, a book lying on a table has less gravitational potential energy than the same book on top of a taller cupboard, and less gravitational potential energy than a heavier book lying on the same table. An object at a certain height above the Moon's surface has less gravitational potential energy than at the same height above the Earth's surface because the Moon's gravity is weaker.”  (http://en.wikipedia.org/wiki/Potential_energy#Gravitational_potential_energy)

In this lesson, students will also use their model race cars to investigate and demonstrate the relationship between force, mass, and acceleration.  Newton’s 2nd law of motion identifies this relationship using the formula F=m*a (Force = mass * acceleration)  During the testing phase of this lesson, students should have the opportunity to see how as they increase the mass of their model cars, they will in turn see an increase in force and acceleration.  

Friction is a force that opposes motion between objects that are touching.  Students will use their models to try to identify variables that may reduce effects of friction and therefore increase the acceleration and the distance that their model will travel.  

Background needed by students:  

Students will need to have prior knowledge that energy is required for an object to move or experience a change in shape or temperature.  In this lesson, students will build on their basic knowledge of energy and become able to distinguish between the potential and kinetic energy of an object.  Students should also have a basic understanding that objects only move when a force is applied.  Students will need to understand the meaning of the terms force, mass, acceleration, energy, motion, friction, and work.  In this lesson, students will be investigating the proportional relationship between the force applied to an object, the mass of the object, and the object’s acceleration.   Students will also need to have a familiarity with good experimental design in order to be able to design an investigation to test variables that affect the design of their race car.  



Procedures:

Activity 1 - Race Car Design (2-3 50 min class periods)
Introduce students to the idea of an engineering competition to produce vehicles that are fuel efficient while still providing speed and comfort for consumers.  Begin by showing students a clip from the Progressive X Prize Competition website:  http://www.progressiveautoxprize.org/
The awards ceremony video has a great summary of the competition in the first 12 minutes.  

Tell students that they will be participating in a similar competition against their classmates to design a model car that will travel the furthest distance and/or the greatest speed with the most fuel efficiency.  The model cars are to be powered only by the gravitational potential energy of the model, so fuel efficiency will be determined by which cars can travel the greatest distance per Joule of gravitational potential energy.  

Explain to students that gravitational potential energy is the energy stored in an object due to it’s position and the force of gravity that is acting on the object.  This would be a good time to review the difference between mass and weight.   Mass is a measure of the amount of matter than an object contains.  The weight of an object is a measure of the force of gravity that is pulling on an object due to it’s mass.  Allow students to investigate the effect on acceleration and distance traveled as they add or subtract mass on their model cars.  Students should record their observations in their science notebook to help them determine an optimum weight for their car to travel at the highest speed or the furthest distance.

Remind students that in order for an object to move, a force must act on the object.  Demonstrate with a toy car and a ramp what happens when the car is pushed down the ramp with small force, and then with a larger force.  Ask students to describe how the acceleration of the car was affected with increased force.  Have students record their observations in their science notebooks.  This would be an excellent opportunity to explore or review Newton’s 2nd law of motion and the relationship between force, mass, and acceleration.
Next, ask students to predict what would happen if the car was not pushed at all.  Would it still travel down the ramp?  Ask students what force would make the car move and guide their answers toward a conversation about gravitational force.  Explain that Earth’s gravitational force causes all objects in free fall to accelerate at about 9.81 m/s/s.   

Ask students to brainstorm a list of forces that might slow their car down, or prevent it from accelerating at 9.81 m/s/s.  Ask guiding questions until students mention forces of friction and air resistance.  You could demonstrate the effects of air resistance by dropping a ping pong ball and a golf ball.  Be sure students understand that the golf ball does not fall faster due to higher mass, but that the motion of the ping pong ball is affected more by air resistance due to its lower mass.

Tell students that their challenge is to design a model race car that will minimize the effects of friction and air resistance so that they will have the car that will travel the fastest or the furthest with the most fuel efficiency. Students should construct their models, then test their models on a ramp to record distance traveled and the acceleration.  Students will also need to record the mass of their car.

Once students have finalized their design and collected their data on acceleration and distance traveled, they could figure out the fuel efficiency of their car in distance traveled per Joule of gravitational potential energy.  (The fuel for the students’ models will be the GPE measured in Joules.)  To figure the GPE - use the following equation:  

GPE = (Height from ground) * (acceleration of gravity = 9.81 m/s/s) * (mass of object)

Then have the students measure the distance that their car travels with the maximum amount of GPE starting at the top of a ramp.  Students can then determine the fuel efficiency of their car by dividing the distance by GPE.  (Answers should be given in meters or centimeters / Joule)  Award prizes for the most fuel efficient models.

Students should have access to a standardized ramp with a height that is determined by the teacher ahead of time.  Students may replicate this ramp for testing purposes.  

Activity 2 - Race Car Testing and Modification (2 50 min class periods)
Once students have designed their race car and collected some initial data on mass, acceleration, GPE, and fuel efficiency, they should use the Need For Speed Investigation Guide (Appendix D) to design a controlled experiment to test a chosen variable that could improve the fuel efficiency or speed of their vehicle.  

Begin by asking students to brainstorm a list of ways that might be able to make their car travel faster or farther without adding any additional force or raising the ramp.  This would be good time to explain that one way to increase GPE is to increase the height of the object.  Since students will be racing from a standardized height, they are going to have to investigate other ways for increasing the GPE (fuel) and/or the efficiency. Have students record their ideas on their investigation guide.  

Students will need to choose one variable at a time to investigate.  Some possible variables they may choose are:

• mass of car
• placement of mass (front, middle, rear of car)
• wheel size, placement, number wheels, materials, alignment
• car body: shape, materials
• use of lubricants: graphite, vegetable oil, etc.

Students may identify other variables to test.  Teacher should approve of the chosen variable before students design their investigation.

Students will use the Need For Speed Investigation Guide to set up a data table to record results from multiple trials as they test their chosen variable.  Students will be asked to identify the controls they used to ensure a fair test.  After data are collected, students will need to analyze their data to determine what changes they could make to their design to improve speed or fuel efficiency.  Students may design multiple investigations to test multiple variables as time permits.  Be sure students understand that any changes that they make to their original design must be justified by data they collected in a controlled experiment.


Activity 3 - Race Car Presentation (1-2 50 min class periods depending on number of student groups)

Once students have completed testing and finalized their design, they will complete a brief presentation for their classmates to showcase their design.  Students will be given a presentation rubric (Appendix A) to guide their work.  Presentations should show how the design evolved or changed from the original design to the finished product due to data collected in the testing phase.  Students should also be able to clearly explain how they calculated the gravitational potential energy of their model car.  Students should also describe the relationships between potential and kinetic energy and between force, mass, and acceleration.  As part of their presentation, students should describe how they used these scientific concepts in the design of their model car.  Students should think of these presentations as a type of sales pitch for their particular design.  Encourage students to incorporate pictures or videos that they took during their design and testing phase.  Students may even want to show multiple examples of their design in process.  

As students listen to the presentations being made by their classmates, they should answer the following questions in their science notebook:

• What worked well with this design?
• How was the final design an improvement over the original?
• How did the group correctly use scientific methods to test their design?
• How could this group have improved their testing methods?
• What suggestions would you give for improving their design?

Management suggestions:
Automotive Engineers work in teams.  To make these activities as realistic as possible, students should work in groups of 2 or 3.

Have several examples of materials available to spark student thinking about how they will construct their model, but avoid showing students a completed model.  Students should develop their own unique design. Some ideas for materials are listed in the materials section of this lesson plan.

When models are completed, invite parents or students in other classes to watch the races and/or design presentations.  You could request a larger meeting space like a library or gym to hold the competition and presentations if the classroom space will not accommodate guests.

Encourage students to take photos or video throughout their design and testing process to be used in their final presentation.


Safety cautions:
Students will  be working with a variety of tools and materials to complete their designs.  Be sure students wear eye protection if working with sharp instruments or heat.  Clothing protection may be needed if students are working with lubricants or adhesives.  Remind students to keep a neat working area and put away materials when they are finished so that damage does not occur due to clutter.

Decision-making or critical thinking:
Students will be making decisions and using critical thinking as they develop the design of their race car. There were be some parameters for mass and ramp height that students will have to abide by, but otherwise, students will be completing and modifying their own design.  Students will be analyzing data from an investigation that they construct to test their design.  Based on their data, students will be modifying their design to produce the fastest or longest traveling car while still meeting the mass requirement.

Students will also be evaluating the designs and the testing procedures utilized by their classmates as they listen to final presentations.

Extensions:
Students could also determine how many Joules of GPE would be needed to get their model to travel a set distance (100 m).  Students will need to use the efficiency of their vehicle to determine how many Joules of GPE are necessary, then they can use the equation for GPE to find the needed values for their car’s mass at a given ramp height, or find the needed ramp height with a given vehicle mass.  Students could include their efficiency data in their design presentation.  

Since designers also must consider the tastes of the buying public when producing their products, you may want to conclude this lesson with a classroom car show.  Allow students to vote on their favorite designs to recognize those cars that excel in form as well as function.  

Assessment methods: (rubric in Appendix A)

Formative assessments will include student responses during classroom discussion and question/answer sessions.  Student writing in their science notebooks will also be reviewed and evaluated throughout this lesson.  Teacher will monitor design and testing phase to check for understanding of scientific concepts being addressed and for correct use of scientific and engineering practices.  

Summative assessments will include the group completion of the Need For Speed Investigation Guide (Appendix D) as well as the final presentation rubric printed on the following page.  Students will also be assessed on their responses to the peer evaluation questions that they complete in their science notebooks.

Rubric for Final Presentation:

Source(s): (Appendix B)
This is an original lesson plan inspired by investigations called Pencil Car Race and Indy 500 in Middle School Science with Vernier written by Donald Volz and Sandy Sapatka.  

This lesson also references video and other content from the Progressive Automotive X Prize website:  http://www.progressiveautoxprize.org/, however the content of this lesson is original to this author.

Background information on gravitational potential energy was obtained from: http://en.wikipedia.org/wiki/Potential_energy#Gravitational_potential_energy

Materials:
Students will need a variety of materials to design their race cars.  Here is a list of ideas to start with, but students may use other materials available in the classroom as long as the same set of materials is made available to all student groups.

• Wheels:  cardboard or cardstock, paper towel or toilet paper rolls, craft foam, plastic container lids, any circular material should work.
• Axles:  toothpicks, paper clips, pencils, craft sticks, nails, etc.
• Body: cardboard or cardstock, paper towel or toilet paper rolls, construction paper, plastic containers, egg crates, wood blocks, Legos, etc.

See Figure 1 below for an example of a model race car using simple classroom materials:
Figure 1
Students will also need scissors, glue (or other adhesives), tape, rubber bands, craft wire, wire cutters, and other tools permitted for use by parents and teachers.

Students should be provided with materials for building ramps to test their cars and a standardized ramp should be provided for the final competition.

Students may use LabQuest or other CBL device to collect data on acceleration.  Balances should be provided to measure mass.  Students will also need stopwatches and meter sticks.  

Correlations to National Standards and Arkansas Frameworks: (Appendix C)

Next Generation Science Standards addressed:

• MS.PS-E a - Construct an explanation of the proportional relationship pattern between the kinetic energy of an object and its mass and speed.
• MS.PS-E b - Use representations of potential energy to construct an explanation of how much energy an object has when it’s in different positions in an electrical, gravitational, and magnetic field.
• MS.PS-E g - Design and evaluate solutions that minimize and/or maximize friction and energy transfer in everyday machines.
• MS.PS-FM b - Communicate observations and information graphically and mathematically to represent how an object’s relative position, velocity, and direction of motion are affected by forces acting on the object.
• MS.PS-FM d - Use mathematical concepts and observations to describe the proportional relationship between the acceleration of an object and the force applied upon the object, and the inversely proportional relationship of acceleration to its mass.
• MS.ETS-ED b - Develop a better design by combining characteristics of different solutions to arrive at a design that takes into account relevant scientific principles and better meets the needs of society.
• MS.ETS-ED c - Compare different designs by building physical models and running them through the same kinds of tests, while systematically controlling variables and recording the results to determine which design performs best.
• MS.ETS-ED e - Refine a design by conducting several rounds of tests, modifying the model after each test, to create the best possible design that meets the most important criteria.
• MS.ETS-ED f - Communicate information about a proposed solution to a problem, including relevant scientific principles, how the design was developed, how it meets the criteria and constraints of the problem, and how it reduces the potential for negative consequences for society and the natural environment.

Arkansas Student Learning Expectations (Benchmarks) addressed:

• PS.6.6.3 Conduct investigations of various forces using SI units (newton).
• PS.6.6.4 Recognize and give examples of different types of forces:  gravitational forces, magnetic forces, friction.
• PS.6.6.7 Describe the effects of force:  move a stationary object, speed up, slow down or change the direction of motion, change the shape of objects.
• PS.6.6.8 Conduct investigations to demonstrate change in direction caused by force.
• PS.6.6.9 Conduct investigations to calculate the change in speed caused by applying forces to an object.
• NS.1.6.2 Apply components of experimental design used to produce empirical evidence: hypothesis, replication, sample size, appropriate use of control, use of standardized variables
• NS.1.6.4a Construct and interpret scientific data using: data tables/charts
• NS.1.6.3 Compare scientific data using mean, median, mode, and range using SI units
• NS.1.6.5 Communicate results and conclusions from scientific inquiry