Chapter1: principles of Design Engineering Design and Problem Solving

Introduction/Description The Intro-Mini Project will introduce the engineering design process through a problem solving scenario, as well as the concept of Coefficient of Restitution (COR), and sketching and technical drawing. You will work in project teams and present your data and solutions to the class.

Chapter 1: Outline Engineering Careers History of Engineering and Innovation Importance of Innovation Future Challenges of Innovation

Objectives and Results To review scientific concepts of kinetic energy, potential energy, and energy transfer. To determine the coefficient of restitution (COR) for various sports balls. To understand elastic and inelastic collisions. To practice sketching and creating technical drawings of various sports balls using graphic tools. To apply the concept of engineering design to a problem scenario. To reinforce collaborative and communication skills.

Objectives and Results, cont. Students will be able to explain the concept of engineering design. Apply engineering design concepts to a problem scenario. Practice sketching technical drawings and engineering notebooks. Reinforce collaborative and communication skills.

Schedule of Assignments Class Period(s) Topic(s) Reading Assignment 1 Provide information to complete the Mini Project finding the coefficient of restitution for various sports balls Vocabulary Rubrics Coefficient of Restitution Internet article; Ball Bounce article #1-Individual; Complete reading and select teams 2 Collect data for Mini Project Chapter #2-In teams of 2-3; Calculate the coefficient of restitution for various sports balls, sketching, and recording data collected 3 Create presentation of data #3-In teams of 2-3; Develop conclusions and create presentation of Mini Project 4 Share PowerPoint presentation with class #4-In teams of 2-3; Complete the communication & presentation of your data following the rubric given; complete the mini engineering notebook (Daily)

Vocabulary Coefficient of Restitution Elastic Collision Energy Transfer Inelastic Collision Kinetic Energy Potential Energy Coefficient of Restitution (COR): a fractional value representing the ratio of velocities after and before an impact (sometimes to referred to as “bounciness”); an object with a COR of 1 collides elastically, while an object with a COR < 1 collides inelastically Elastic Collision: an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter; elastic collisions occur only if there is no net conversion of kinetic energy into other forms Energy Transfer: the transfer of energy from one body to another Inelastic Collision: a collision in which kinetic energy is not conserved Kinetic Energy: energy that a body possesses by virtue of being in motion Potential Energy: energy which an object has because of its position; it is called potential energy because it has the potential to be converted into other forms of energy, such as kinetic energy

Team Building What is a team? “A team is a small group of people with complementary skills who are committed to a common purpose, performance goals, and approach for which they hold themselves mutually accountable.” Katzenbach, Jon R., and Smith, Douglas K., The wisdom of teams: creating the high- performance organization; Jon R. Katzenbach, Douglas K. Smith Harvard Business School Press, Boston, Mass.: 1993 What is a team?

What is Team Building? Creating a successful team can be a challenging task. Teams must rely on the process called team building. Team building integrates individual skills and resources into a unified effort.

Team Building Actions Team building involves the following actions: Encouraging team members to examine how they currently work together Portraying ideal ways of collaborating Exploring the gaps and weaknesses they currently suffer from Establishing action plans for implementing more effective ways of cooperating

What is a Team Leader? Team building is best aided by a team leader or a facilitator. A team leader or facilitator performs several tasks: Helps the group learn about itself Observes team meetings Gives feedback and key observations to the team

What Does a Team Leader Do? A team leader probes, questions, listens, watches for nonverbal cues, and stimulates problem solving. The intended results include a team that is open to new alternatives, who is aware of their resources, has the ability to think and act independently, and is willing to explore the consequences of their current or proposed actions.

Benefits of Team Building There are several benefits for executing team building: Improves morale and leadership skills Clearly defines objectives and goals Improves processes and procedures Improves team productivity Identifies a team's strengths and weaknesses Improves the team’s ability to problem solve We need team building because it builds team morale and leadership, builds trust, reinforces appropriate behaviors of team members, and helps team members to become more flexible and adaptive to solving problems.

Team Building Assignment In your team, discuss leadership roles and responsibilities of team members. Select roles for each team member. Write and agree to team contract. Have your teacher approve your team contract. Discuss implications of team building in the field of engineering.

Energy Energy Transfer – moving energy from one body to another Kinetic Energy - energy that a body possesses by virtue of being in motion Potential Energy - energy which an object has because of its position Energy Transfer - moving energy from one body to another Kinetic Energy - energy that a body possesses by virtue of being in motion Potential Energy - energy which an object has because of its position; it is called potential energy because it has the potential to be converted into other forms of energy, such as kinetic energy Roller Coaster Graphics: “The cars of a roller coaster reach their maximum kinetic energy when at the bottom of their path. When they start rising, the kinetic energy begins to be converted to gravitational potential energy. The sum of kinetic and potential energy in the system remains constant.” http://en.wikipedia.org/wiki/Kinetic_energy

Loss of Energy Mechanical energy is the sum of the energy of motion: KE (Kinetic Energy) = ½ mv2 GPE (Gravitational Potential Energy) = mpg where m = mass, v = velocity (speed), g = gravitational pull, and p = potential energy. The total energy in a system is conserved, but when a ball bounces, it loses mechanical energy because the collision between the ball and the surface is inelastic. The amount of energy that the ball loses will depend on the coefficient of restitution, a ration of its pre-collision velocity to its post-collision velocity.

Coefficient of Restitution The coefficient of restitution (COR), or bounciness of an object, is a fractional value representing the ratio of velocities after and before an impact (vup/vdown). An object with a COR =1 collides elastically. < 1 collides inelastically. The coefficient of restitution (COR), or bounciness of an object, is a fractional value representing the ratio of velocities after and before an impact. COR = vup/vdown An object with a COR equal to 1 collides elastically. less than 1 collides inelastically. Bouncing ball strobe graphic: http://en.wikipedia.org/wiki/File:Bouncing_ball_strobe_edit.jpg

Elastic and Inelastic Collision Elastic Collision - an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter. Inelastic Collision - a collision in which kinetic energy is not conserved

Determining Coefficient of Restitution The amount of energy that the ball loses will depend on the coefficient of restitution (COR), a ratio of its pre- collision velocity (vup) to its post-collision velocity (vdown). Coefficients of Restitution YouTube video Coefficients of Restitution YouTube video: http://www.youtube.com/watch?v=0bis1cA842c

Using the Velocity Formula In order to find velocity (v), use the height of the ball after it hits the ground (h) and put it in the following equation: v = √(2gh) where v = velocity, g = 9.8m/s2, and h = height when ball is dropped. Coefficient of Restitution = √(2gh)) / √(2gH) = √(h/H) where H is the initial height of the ball.

Ball Bounce Article “The dynamics of a collision between a ball and another object can be determined in principle, from the individual conditions and the functional form of the force acting on the ball.” Ball Bounce Experiment Dynamics of Bounce Experimental Techniques and Results Comparison of Static and Dynamic Hysteresis Curves Ball Variations Effects of Ball Speed Student Handout: Ball Bounce Handout http://www.physics.usyd.edu.au/~cross/PUBLICATIONS/BallBounce.pdf “The dynamics of a collision between a ball and another object can be determined in principle, from the individual conditions and the functional form of the force acting on the ball.” Rod Cross, Am J. Phys, 67 (3), March 1999, 222-227. Dynamics of Bounce Experimental Techniques and Results Comparison of Static and Dynamic Hysteresis Curves Ball Variations Effects of Ball Speed

Student Scenario It’s the beginning of the school year. Students are interested in joining an extracurricular sporting team. There are several female and male sporting teams to choose from at the high school. What are the sporting teams at your high school? Research and list the various types of extracurricular sporting teams available for both female and male students. Gather the types of balls used for each extracurricular sporting team. Driving Questions What is the coefficient of restitution (COR) of the various sporting balls? What are the female and male sporting teams at your high school? What are the types of sporting balls used by the female and male students? Why might different balls be used for different sports?

Student Project Basics Individually and in teams, you will calculate the coefficient of restitution (COR) for at least 5 sports balls, create sketches and diagrams in your engineering notebook for each ball, design a new type of ball for at least one sport, document the design process your team went through, and present your findings to the class.  

Step 1: Getting Started Determine the female and male sporting teams on campus. Gather the types of sports balls used by each female and male sporting team on campus and document them in your engineering notebooks.

Step 2: Collecting Data Gather a meter stick, balance (to explore relationship between mass and energy for extension applications), and random measurement equipment (figure out what you really need to use), timers, graduated cylinders, balances, forces, scales, etc.

Step 3: Analysis Sketch designs of the various sports balls on graph paper. Create technical drawings of the various sports balls using software graphic tools. Demonstrate teamwork and professionalism. Determine the height of the ball after it bounces. Determine the coefficient of restitution (COR) of the sports balls.

Step 4: Engineering Design Considering your data and what you learned about the behavior of each ball, would any of the balls perform better in another sport? Explain. Design a new type of ball for at least one sport. There is not necessarily a right or wrong answer. Create a presentation about the coefficient of restitution of the various sports balls and the new type of ball you are proposing for at least one sport. Be sure to document your procedure, data collected, and conclusions drawn. Sketch design of the various sports balls on graph paper. Create technical drawings of the various sports balls using software graphic tools. Demonstrate teamwork and professionalism. Determine the speed of the sports balls right before it hits the ground and then right after it bounces.

Step 5: Presentation Prepare a Microsoft PowerPoint team presentation of your work (rationale and results). Reflect on the concepts of energy and collisions. Explain what you have learned and why different balls might be used for different sports. Describe the new type of ball your team designed for at least one sport. In as much detail as possible, explain the steps of the process your team went through in order to come up with the new ball design.

Conclusion/Questions to Consider Why is the coefficient of restitution of a ball so important in sports? What are the factors that determine the COR? What might happen if you tried to use the “wrong” ball for a sport?

Credits ClipArt; http://www.clipart.com/en/ Images; http://commons.wikimedia.org/wiki/Main_Page Slide 19 Coefficient of Restitution video; from YouTube user; Gaby Salguero http://www.youtube.com/watch?v=0bis1cA842c