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Mechanics Reform: Engineering Challenges and Problem Solving Strategies

Explore the fundamentals of mechanics in this introductory lecture. Topics include modeling physical problems, software utilization, and problem posing techniques. Learn about rigid bodies, deformable bodies, and fluids. Discover Newton's Laws, measurement basics, and unit conversions. Get ready to delve into the world of engineering challenges and problem-solving strategies.

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Mechanics Reform: Engineering Challenges and Problem Solving Strategies

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  1. ME 221 StaticsFall 2003 Mr. Hinds 3523 EB hinds@msu.edu

  2. Administrative Details • Syllabus will be posted on the web • www.angel.msu.edu (Angel) • Lecture attendance • Web will be used for announcements but not all important announcements given in class may be posted on the web • Bring books to class for example problems • Sample problems will be an integral part of lecture • Lecture behavior • Class size requires professional conduct Lecture 1

  3. Administrative Details cont. • Exams • Dates set and given on syllabus • first test date set for 100% refund drop date • Format • closed book, closed notes, calculator • Excused absences: See syllabus • Philosophy • Most problems like HW; some problems conceptually same as HW but somewhat different Lecture 1

  4. Administrative Details cont. • Homework & quizzes • solutions will be posted • all or partial problems will be graded • lecture quizzes used as “scrimmages” • quizzes in the last 15-20 minutes of lecture • similar to assigned homework • generally announced - some unannounced Lecture 1

  5. Administrative Details cont. Questions?? Lecture 1

  6. ENGINEERING… The Future and the Challenges…..?? Lecture 1

  7. Problem Solving Strategy 1 - Modeling of physical problem (free body diagram) 2 - Expressing the governing physical laws in mathematical form 3 - Solving the governing equations 4 - Interpretation of the results Lecture 1

  8. Mechanics Reform • Textbook offers a departure from past standards • recognizes the power of computer software in solving problems • MathCAD, MatLab, Maple, Mathmatica, VB, etc. • calculators may be effectively utilized as well • before using the software, the problem must be properly posed • posing the problem will be emphasized in this class Lecture 1

  9. Mechanics Reform cont. • Software helps us with: • trigonometry • units conversion • Software does not help with: • envisioning the forces • systems of equations • iterative problems for design purposes • applying the proper laws of physics Lecture 1

  10. Mechanics • Broadly defined as the study of bodies that are acted upon by forces. • Types of bodies • particles (considered rigid bodies) • rigid bodies - relative distance between any two points remains constant throughout motion • deformable bodies • fluids Lecture 1

  11. Rigid Static Statics Static Deformable Mech Matl Dynamic Rigid Dynamics Dynamic Fluid Dyn Deformable Mechanics Overview Lecture 1

  12. And now ... Statics Lecture 1

  13. Chapter 1: Measurement • Newton’s Laws of Motion • Space and Events • Vectors and Scalars • SI Units (Metric) • U.S. Customary Units • Unit Conversion • Scientific Notation • Significant Figures Lecture 1

  14. Basics: Newton’s Laws • Every body or particle continues in a state of rest or of • uniform motion in a straight line, unless it is compelled • to change that state by forces acting upon it. (Law of Inertia) • The change of motion of a body is proportional to the • net force imposed on the body and is in the direction of • the net force. F=ma • If one body exerts a force on a second body, then the • second body exerts a force on the first that is equal in • magnitude, opposite in direction, and collinear. Lecture 1

  15. Law of Universal Gravitation: Any two particles are attracted to each other with a force whose magnitude is proportional to the products of their gravitational masses and inversely proportional to the square between them. F=Gm1m2/r2 where G = 66.73 x 10-12 m3/kg-s2 Lecture 1

  16. y mi x z Basics • Space -- we need to know the position of particles • Event -- position at a given time Lecture 1

  17. Basics cont. • vectors must have direction specified • e.g., velocity, force, acceleration • Two broad quantities • scalars have no direction associated with them • e.g., temperature, mass, speed, angle • Mass -- a scalar that characterizes a body’s resistance to motion • Force -- (vector) the action of one body on another through contact or acting at a distance Lecture 1

  18. International System of Units:The SI system • Length meters m • Time seconds s • Mass kilogram kg • Force Newton N 1 kg m/s2 • See table 1-1 for prefixes Compound units Remember: Speed = distance/time so in SI units, speed is measured in m/s Lecture 1

  19. U.S. Customary Units • Length foot ft • Time seconds s • Mass slug slug • Force pound lb slug ft/s2 • *Remember: W= mg • where g = 32.17 ft/s2 Lecture 1

  20. Numerical Answers • equal 5: then all digits after it are dropped • Significant figures • Use 3 significant digits • If first digit is 1, then use next 3 • Rounding off the last significant digit • less than 5: all digits after it are dropped • greater than 5 or equal 5 followed by a nonzero digit: round up Lecture 1

  21. END OF BASICS Lecture 1

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