N1IR Electronics Blog: June 2012

The engineering design process is the series of steps engineers use to tackle a problem and arrive at a solution. It is a systematic process that yields results, and engineers in every branch of engineering use it.

In today’s activity, you will follow the steps of the engineering design process to tackle the challenge of how to land a ‘spacecraft’ gently enough so the ‘astronauts’ inside remain unharmed. You will brainstorm ideas for a landing system than can cushion a falling spacecraft. Then, you will build, test, evaluate, and revise your design until you meet the challenge.

By the end of Session 1, you will have explored the concepts of potential and kinetic energy, know the steps of the engineering design process, and have seen how they are an effective way to solve a design challenge. You will apply this process in each of the remaining sessions.

Challenge:
Design build, test, and refine a shock-absorbing system that will protect two marshmallow “astronauts” by cushioning them when their cardboard spacecraft is dropped several feet onto a table or floor.

Engineering Focal Question:

How can we develop a shock absorber that can decelerate a vehicle effectively?
Science Focal Question:
How does a shock absorber dissipate kinetic energy?
Learning Objectives:
After completing this session, you’ll be able to:

Use and name each step of the engineering design process and explain how each step contributes to solving a design challenge.
Devise solutions to an open-ended challenge.
Explain how a shock absorber dissipates kinetic energy.
Explain how the choice of materials influences the effectiveness of a shock absorber design.
Describe three commonly held stereotypes of engineers and engineering.
Develop strategies for countering commonly held stereotypes of engineers and engineering with students.

State Standards:
Session 1 directly explores a number of standards listed below. We have also listed several standards related to the Session 1 activities. A teacher teaching these themes and looking for a concrete example or hands-on project could use the Session 1 activities to further develop students’ understandings of these related standards.

Mathematics:(The number before each standard indicates grade level)

Grade 7-8

7.EE Solve real-world and mathematical problems using numerical and algebraic expressions and equations.
7.RP Analyze proportional relationships and use them to solve real-world and mathematical problems.
7.G Draw, construct, and describe geometrical figures and describe the relationships between them.

High School Conceptual Category: Geometry

Congruence - Experiment with transformations in the plane.

Physical Science Standards:

Grade 3–5

5. Give examples of how energy can be transferred from one form to another.

Grade 6–8

1. Differentiate between weight and mass, recognizing that weight is the amount of gravitational pull on an object.
11. Explain and give examples of how the motion of an object can be described by its position, direction of motion, and speed.
13. Differentiate between potential and kinetic energy. Identify situations where kinetic energy is transformed into potential energy and vice versa.

Physics Standards:

Grade 9-12

1.1 Compare and contrast vector quantities (e.g., displacement, velocity, acceleration force, linear momentum) and scalar quantities (e.g., distance, speed, energy, mass, work).
1.2 Distinguish between displacement, distance, velocity, speed, and acceleration. Solve problems involving displacement, distance, velocity, speed, and constant acceleration.
1.3 Create and interpret graphs of 1-dimensional motion, such as position vs. time, distance vs. time, speed vs. time, velocity vs. time, and acceleration vs. time where acceleration is constant.
1.4 Interpret and apply Newton’s three laws of motion.
1.5 Use a free-body force diagram to show forces acting on a system consisting of a pair of interacting objects. For a diagram with only co-linear forces, determine the net force acting on a system and between the objects.2.2 Interpret and provide examples of how energy can be converted from gravitational potential energy to kinetic energy and vice versa.
2.2 Interpret and provide examples of how energy can be converted from gravitational potential energy to kinetic energy and vice versa.
2.3 Describe both qualitatively and quantitatively how work can be expressed as a change in mechanical energy.

Science Inquiry Skills

Grade 9-12

SIS2: Design and conduct scientific investigations.
SIS2: Employ appropriate methods for accurately and consistently
making observations
SIS2: Making and recording measurements at appropriate levels of precision
SIS2:Collecting data or evidence in an organized way
SIS3: Analyze and interpret results of scientific investigations.
Use mathematical operations to analyze and interpret data results.

Technology and Engineering Standards:

Grade 6-8

2.1 Identify and explain the steps of the engineering design process, i.e., identify the need or problem, research the problem, develop possible solutions, select the best possible solution(s), construct a prototype, test and evaluate, communicate the solution(s), and redesign.
2.2 Demonstrate methods of representing solutions to a design problem, e.g., sketches, orthographic projections, multi-view drawings.

Grade 9-12

1.1 Identify and explain the steps of the engineering design process: identify the problem, research the problem, develop possible solutions, select the best possible solution(s), construct prototypes and/or models, test and evaluate, communicate the solutions, and redesign.
1.2 Understand that the engineering design process is used in the solution of problems and the advancement of society. Identify examples of technologies, objects, and processes that have been modified to advance society, and explain why and how they were modified.
1.3 Produce and analyze multi-view drawings (orthographic projections) and pictorial drawings (isometric, oblique, perspective), using various techniques.
1.4 Interpret and apply scale and proportion to orthographic projections and pictorial drawings (e.g., ¼" = 1'0", 1 cm = 1 m).
1.5 Interpret plans, diagrams, and working drawings in the construction of prototypes or models.

Setting the Stage

The Touchdown activity looks at the challenge of landing a spacecraft on the moon. A spacecraft traveling to the moon reaches 18,000 miles per hour, but it needs to slow and land gently enough so the astronauts inside are unharmed. With no atmosphere or surface water to cushion a landing, landers use rocket engines to touch down. Nevertheless, landers are well equipped to absorb shock in case of a hard landing.

So how does all this relate to the engineering design process? The design process is a great way to tackle almost any problem. Since engineers’ initial ideas rarely solve a problem, they try different ideas, learn from mistakes, and try again. The series of steps they use to arrive at a solution is called the engineering design process. Its power lies in clearly defining the problem and then cycling through a Build-Test-Revise process until reaching a satisfactory solution.

Different versions of the design process can have differing numbers of steps and may title them differently, but they all describe a team-based, iterative process that breaks the process of solving a problem into discrete steps. The Massachusetts Science and Engineering/Technology Curriculum Frameworks defines the engineering design process as an eight-step process:
Step 1: Identify the Need or Problem
Step 2: Research the Need or Problem
Step 3: Develop Possible Solution(s)
Step 4: Select the Best Possible Solution(s)
Step 5: Construct a Prototype
Step 6: Test and Evaluate the Solution(s)
Step 7: Communicate the Solution(s)
Step 8: Redesign

Today you’ll make a spacecraft that can land safely when you drop it on the floor. As you test, you’ll find ways to make it work better. By coming up with an initial design and revising and improving it based on testing, you’ll be applying the engineering design process.

Materials

Download Touchdown (PDF) by clicking on the image of the PDF. (Touchdown is from the To the Moon activity guide, funded by NASA and developed by WGBH.

It is also available as Challenge 2 at: http://pbskids.org/designsquad/parentseducators/guides/activity_guide_moon.html

1 piece of stiff paper or cardboard (approximately 4 x 5 inches)
1 small paper or plastic cup
3 index cards (3 x 5 inches)
2 regular marshmallows
10 miniature marshmallows
3 rubber bands
8 plastic straws
Scissors
Tape
Have a digital camera available to document your work!

Preparation

Download the Leader Guide (PDF) by clicking on the page image. These notes provide additional information beyond the activity handout.
Gather the materials listed above and/or on the PDF.

Procedure

Make your lander, following the instructions on the handout.
If you need help....building tips and troubleshooting strategies are available in the leader notes.

Things to think about:

Brainstorm and design. Think about how to build a spacecraft that can absorb shock and have a soft landing.

• What kind of shock absorber can you make from these materials?
• How will you make sure the lander doesn’t tip over as it falls through the air?

Build a shock-absorbing system. Once you build your design, attach the shock absorbers to the cardboard platform.
Add a cabin for the astronauts. Tape the cup to the platform. Put two astronauts (the large marshmallows) in it. (NOTE: The cup has to stay open—no lids!)

While the Design Squad series is all about applying the design process to interesting challenges, one Design Squad guide in particular—the Teacher’s Guide—offers teachers an especially rich set of design process resources.

a) Open the Teacher’s Guide webpage.

b) At the bottom of your screen, you should see a section entitled "The Design Process." Download and read the PDF of the Design Process. If an illustration of the design process would be useful in your classroom, download and print out the poster (in English and in Spanish).

c) In this section, click on and view the five video clips (about 2 minutes each). They are excerpted from the television series and show teams of teenagers in different stages of tackling one of the challenges thrown them by a client. (You can view the full episode [25 minutes] on the Design Squad website.) Each video clips focus in on a specific part of the design process, and you can use them to show students how the design process helps them think creatively about solving a problem. The five clips are:

Identify the Problem - QuickTime video clip
Brainstorm - QuickTime video clip
Design - QuickTime video clip
Build, Test, & Redesign - QuickTime video clip
Share Solutions- QuickTime video clip

d) Optional: In the three units presented on this webpage, you will find seven additional “Design Process” clips. They cover additional facets of the design process, such as working as a team, dealing with frustration when a project bogs down, and resolving differences when there are disagreements within the team. They can be a handy way to discuss additional aspects of the design process with students.
Below is a selection of brief readings and multimedia resources about the central science and engineering concepts in the Touchdown challenge. They define and describe these concepts and provide examples of how we experience these phenomena everyday. Select at least one from each topic. You can apply the ideas in these readings and multimedia resources in your answers to the "Show Your Understanding" questions at the end of this session.

Physics at work

Acceleration Due to Gravity:

Kinetic Energy:

Air Resistance:

Center of mass:

Transcripts for Animations

What Affects How Fast You Coast Down the Hill?

The gravitational force between the Earth and you keeps you on the ground. And that force is your weight. The renaissance scientist Galileo Galilei proved that this gravitational force causes objects, light or heavy, to have the same acceleration when they fall. So does that mean that Nick and Tomas are equally fast? Well, no, and here's why. When you move through the air, you create drag, a force that slows you down. And the faster you go, the greater the drag. When drag matches the gravitational force of your weight pulling you down the hill, you've hit your top speed. To go faster, you can extend the wheelbase so you can lie flat and reduce your drag, or you can add weight to the bike so there's more force pulling down the hill to overcome the drag. So if Nick and Tomas are equally skilled riders, Nick, who’s heavier, should be faster.

How Can Potential Energy Be Used to Do Work?

Stored energy is called potential energy because it has a potential to do work. One way to build potential energy is to raise an object against gravity, like biking up a hill. Once at the top of the hill stored energy can now be used to do work. If a bike coasts down the hill gravity, then converts potential energy into kinetic energy, or energy of motion, by pulling the bike down the hill. And there are many ways to convert potential energy into kinetic energy.

Air Resistance Explanation

Adding streamers really helps to reduce the velocity of the t-shirt. Here’s what’s happening. When the t-shirt travels through the air, it collides with air molecules creating a friction force. This air resistance, or drag, slows down the t-shirt. When air passes over the t-shirt with streamers, the streamers flap and collide with a greater number of air molecules. This increases the drag and slows down the t-shirt even more.