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Shawn Kenny, Ph.D., P.Eng.Assistant ProfessorFaculty of Engineering and Applied ScienceMemorial University of [email protected]
ENGI 1313 Mechanics I
Lecture 01: Course Introduction and GeneralPrinciples
2 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
ENGI 1313 Resources
TextbookEngineering Mechanics Statics and Dynamics, 11th Edition R.C. HibbelerPearson Prentice Hall (ISBN 0-13-221509-8)
3 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
ENGI 1313 Resources
Statics Study PackChapter reviewsAccess to Pearson Prentice Hall website• wps.prenhall.com/
esm_hibbeler_engmech_11
4 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
ENGI 1313 Resources
MUN Engineering Instructor WebsiteCourse information• www.engr.mun.ca/~spkenny/Courses
Professor contact information• www.engr.mun.ca/~spkenny/Contact
Office Hours• Mon. & Wed. (3-5PM)• Other times can be scheduled by appointment
5 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
ENGI 1313 Resources
General Websitesen.wikibooks.org/wiki/Staticswww.mun.ca/orientation/www.etipsforagrades.comwww.studygs.net/
6 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Academic & Administrative Policies
MUN Engineering WebsiteEngineering exam policy• http://www.engr.mun.ca/undergrad/
MUN WebsiteUniversity regulations• http://www.mun.ca/regoff/calendar/
Student policies• http://www.mun.ca/student/policies/
7 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Course Schedule
LecturesDay: Mon., Tue., Wed. & FriTime: 0900-0950 Location: IIC2001
No LecturesOct. 8 & 9 Fall BreakNov. 12 Remembrance Day
8 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Planned Lecture Schedule
9 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Course Perspective
Educational ProcessCritical thinkingMaking mistakesAsking questionsLearningApplying knowledgeEngagementProfessional development
10 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Course Perspective
Fundamental Engineering CourseMechanicsFoundation to build upon
Work EthicRegular study habits• Lecture and tutorial schedule is known
Critical thinking & problem solving…Critical thinking & problem solving
11 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Objective of the Lecture Notes
to explicitly follow the textbookto provide complement the textbook by providing additional worked examplesto occasionally present complementary material that illustrates practical engineering applications of the theory
12 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Lecture 01 Objectives
to introduce field of mechanicsto introduce some fundamental conceptsto review units of measurement and systemsto provide guidance on engineering calculation procedures and analysis
13 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Introduction to Mechanics
Mechanics
Rigid BodyMechanics
DeformationMechanics
FluidMechanics
• Statics• Dynamics
This course only examinesRigid Body Mechanics: Statics
14 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
General Principles
StaticsEffect of loads on bodies in static equilibrium• Balanced loads• At rest or under motion at constant velocity
15 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
General Principles
KinematicsEffect of motion without consideration of loads
16 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
General Principles
DynamicsEffect of loads on bodies in motion• Unbalanced loads• Acceleration
17 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Brief Historical Perspective
Engineering Mechanics and PrinciplesGeometryEmpirical
Societal ApplicationsMilitaryCivilianShipbuilding
18 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Simple Machines
Inclined planeWedgeScrew
LeverPulleyWheel and axle
19 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Simple Machines
Inclined Plane
20 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Simple Machines
Lever
21 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Simple Machines
Lever
22 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental Concepts
IdealizationsParticle• Constant mass• Negligible size
23 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental Concepts
IdealizationsRigid Body• Combination of particles• Finite size• Relative position of
particles remain fixed• No internal deformation
Deformable Body
P P
Rigid Body
P P
24 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental Concepts
IdealizationsConcentrated Force• Load effects acting
at a point on a body• Load acts on small
dimensions relative to body size
25 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental Concepts
Newton’s Laws of MotionBasis of classical mechanicsMotion ≡ Momentum
• Massive, rigid body• Empirical• Inertial reference frame
(no acceleration)
vmprr
=
26 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental Concepts
Newton’s 1st Law – InertiaParticle equilibrium• Rest• Constant velocity
Unbalanced forces• External• Change in velocity, acceleration
F1
F2
F3
V = 0, v
27 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental Concepts
Newton’s 2nd Law – AccelerationObject in motionUnbalanced external forcesAcceleration• Proportional to force magnitude• Direction of applied net unbalanced force
( ) amvmdtdF
rrr==
28 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental Concepts
Newton’s 3rd Law – Reciprocal ActionAction ⇒ ⇐ Reaction• To every action
there is an equal and opposite reaction
• Equal force magnitude
• Opposite force sense or direction
29 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental Concepts
Newton’s Law of Gravitational Attraction
Point-to-point mass attraction through centers• Force ∝ point mass
1 / distance2
221
rmmGF =
30 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental Concepts
WeightForce acting on particle due to gravityg = acceleration due to gravity• Varies altitude, latitude ⇒ not absolute• Standard is 9.80665 m/s2
gmrmmGW 2
e ==
31 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental ConceptsPhysical Quantities
Characteristics• Measurement process• System of units
Length (L)• Distance, size• Relative position of points in space
Time (T)• Sequence or succession of events
Mass (M)• Intrinsic property of matter• Relative action between bodies
32 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Fundamental Concepts
ForcesType• Direct contact• Electromagnetic• Gravitational
Characteristics• Magnitude• Direction• Point of application
33 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Units of Measurement
Standardized Quantity Physical PropertyScientific method ⇔ reproducibleEconomic and scientific drivers
Historical ContextHuman body• Examples: digit, palm, cubit
Variability• Examples: Arabic, Egyptian, Greek, Roman
34 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Units of Measurement
International System of UnitsUnified, rational system • Units of measurement• Decimal system
35 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Units of Measurement
Imperial and US CustomarySimilarities and differencesMultiple units of measurement• Length ⇒ inch, foot, chain, furlong• Mass ⇒ grain, ounce, pound,
Relatively more complex rules for conversion• 12 inches = 1 foot• 5280 feet = 1 mile• 16 ounces = 1 pound (mass)
Confusion on units• Pound force versus pound mass
36 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Units of Measurement
Base UnitsFundamental structure for the system of units • SI ⇒ meter (m), kilogram (kg), second (s)• FPS ⇒ foot (ft), pound (lb), second (s)
37 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Units of Measurement
Derived UnitsPhysical lawsBase units
Compound UnitsArea, volume
M⋅L2⋅T-2kg⋅m2⋅s-2PaPressureM⋅L⋅T-2kg⋅m⋅s-2NForce
M⋅L-1⋅T-2kg⋅m-1⋅s-2JEnergy
DimensionBase UnitsSymbolQuantity
38 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Engineering Calculations
Significant Figures and RoundingMeasurement tools and error• Basis of engineering data• Precision versus accuracy
Computational tools• Numerical precision • Constants (e.g. e, π)
Consistent Use• Measurement ⇒ meters• Reporting ⇒ millimeters
39 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Engineering AnalysisProblem Statement
ObjectiveData and diagramsKnown and unknown quantities
Applicable TheoryAssumptions, limitations and constraints
Problem SolutionDimensionally homogeneous, consistent unitsSignificant figures and rounding
AssessmentEngineering judgment, common sense
40 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
Representative Problems
Hibbeler (2007) Textbook
Study PackReview questions 1 to 8
5-10minEasy1-1 to 1-1610-15minMedium1-17 to 1-20
Estimated TimeDegree of DifficultyProblem Set
41 ENGI 1313 Statics I – Lecture 01© 2007 S. Kenny, Ph.D., P.Eng.
ReferencesHibbeler (2007)http://wps.prenhall.com/esm_hibbeler_engmech_1http://en.wikipedia.orgwww.royalwwc2007.comhttp://www.liebherr.com/lh/www.ultimaterollercoaster.comhttp://www.rlphotos.com/http://www.world-mysteries.com/gw_tb_gp.htmhttp://www.starlight-theatre.ca/images/013.JPGhttp://www.slrugby.com