What is Engineering ? How does it differ from science?

1. What is Engineering? How does it differ from science? iPod Science: DESCRIBE EXPLAIN Parameters: θ, Ψ, ρ, σ2,☺,λ, Ǻ, g, ћ, H2C5OH, . . . Starting salary: $37.5K (chemist) Engineering: INVENT DESIGN BUILD Parameters: $ Starting salary: $59.5K (chemical engineer) spandex

2. Siting a biological incinerator Designing a fuel-efficient car Cooking dinner Building a house Mathematics/statistics Physics Economics Art Social studies Political science Environmental science Chemistry

3. “Education is what’s left after you’ve forgotten all the facts” Ben Franklin Albert Einstein Oscar Wilde “Don't let schooling interfere with your education” Mark Twain

4. Engineering is problem-solving

5. Schools, in contrast to the rest of the world, focus on the acquisition of generalized learning. Schools aim to teach general skills and theoretical principles on the assumption that, once acquired, these skills can then be used in a wide variety of settings. However, studies of expert performance indicate that expertise does not come about primarily from the application of general skills, but involves the use of situationally specific, relevant knowledge. General skills have no actual use in the real world. Lauren. B. Reznick (1987), The 1987 Presidential Address: Learning in School and Out

6. What is learning? Synthesizing theory and knowledge in order to solve problems: Not just theory out of context--the “what”. But also the “why”, “when”, and under what conditions the theory may be invoked to solve a problem. Learning is also discovering what doesn’t work. ". . . a failed structure provides a counterexample to a hypothesis and shows us incontrovertibly what cannot be done, while a structure that stands without incident often conceals whatever lessons or caveats it might hold for the next generation of engineers." Henri Petroski, To Engineer Is Human

7. Best educational technique: Apprenticeships Graduate - student training Medical residency programs Plumber’s apprenticeships Music lessons Tutoring rather than lecturing! Promoting self discovery! Showing how to learn!

8. Some vehicles for learning Problems “out of chapter” Assignments that involve efficiency, cost, functionality, accuracy Back-of-the-envelope problems: “Fermi questions” Experiments to deduce underlying principles Hands on--laboratories, virtual laboratories, projects Written and oral presentation

9. Assign projects 1) Properties of materials 2) Materials laboratory 3) Theory of structures 4) Design a bridge to specification 5) Build it 6) Test it

10. If you have to lecture. . . • Do’s • Introduce each topic or subtopic by posing a problem • Suppose we need to devise a robot that moves toward light. . . • Suppose we want to separate fat from gravy for a Thanksgiving dinner. . . • Suppose we want to bid on a tree as material for a toothpick factory. . . • Suppose we need a bridge to support the weight of a car. . . • Suppose we would like to deduce the period of a pendulum. . . • Continually ask “why” • Why do we want to do this? • Why do we care? • Why digital instead of analog? • Why binary instead of decimal?

11. If you have to lecture. . . • Do’s (cont.) • Ask the complementary question “Why not?” • Why not use Elmer’s glue (or a glue gun) on spaghetti bridges? • Why not measure the weight of a single penny on a postal scale? • Why not use titanium to build bridges?

12. If you have to lecture. . . • Do’s (cont.) • Ask “what?” • What tools/principles can we use on this problem? • finding forces in members attached to a pin joint on a stationary structure • separating alcohol from water • improving the accuracy of a measurement • What are the conditions under which XXXX will/will not work? • Can we have a stone lintel that spans 20 feet? • When will a model yield characteristics of its full-scale counterpart? • What does it mean if the mass entering a control volume does not equal the mass leaving a control volume?

13. If you have to lecture. . . • Do’s (cont.) • Give examples and counter examples • Give reasons for each step in solving a problem (the solution is less important than the strategy for approaching it) • Pose sub-problems, i.e., “what if?” • Relate to other fields • mass conservation vs. Kirchoff’s laws • heat flow vs. electron flow vs. particle diffusion (gradient transport)

14. If you have to lecture. . . • Don’ts • Don’t present theories/calculations without context • Don’t use ambiguous or loosely defined terms • Don’t give “plug and chug” problems (maybe it’s OK occasionally) • Don’t present topics without placing them within a “bigger picture”

15. A Problem Describe three entirely different (but practical) ways for determining the area of the darkened region to within 0.1%. Pick one. Then deduce the area (in cm2). Would a different method give a more accurate result with less effort? Explain. Might one method be better for rough estimates, another better for precise estimates. Explain. Does the effectiveness of your methods depend on the shape of the figure? Explain.

16. Some possibe answers: 1) Superpose a finely-spaced grid over the figure and count squares  2) Cut out the figure and weigh it. Then compare that weight to that of a piece of paper of known area. If the weight is too small to be measured with an available scale, transfer the figure to another piece of uniformly-dense material which is in the range of your scale.  3) Throw darts (figuratively, of course). Draw a rectangle (whose area can be calculated) which completely encloses the figure. Pick random points within the rectangle and count which ones fall within the darkened figure. The ratio of the number of those points within the darkened area to those within the entire rectangle can be used to estimate the darkened area. (Monte-Carlo integration.)

17. More possible answers. . . 4) Divide the darkened figure into local regions which can be piecewise integrated numerically.  5) Use a “polar planimeter”—a gadget which mechanically integrates the area defined by a closed curve. (How does a planimeter work?)  6) Draw a rectangle on the darkened region of known area. Computer-scan the darkened figure. Write a program to count the number of pixels of the darkened color.Compare that number with those pixels within the rectangle. 7) Build a container whose cross-section is that of the darkened figure. Fill the container with 1000cc of water and measure the water level in the container.