statics

1. COURSE:CE 201 (STATICS)LECTURE NO.:0101FACULTY:FACULTY:DR. SHAMSHAD AHMADDR. AHMADDEPARTMENT:DEPARTMENT:CIVIL ENGINEERINGCIVIL ENGINEERINGUNIVERSITY:UNIVERSITY:KING FAHD UNIVERSITY OF PETROLEUM & MINERALS, DHAHRAN, SAUDI ARABIA& ARABIATEXT BOOK:TEXT ENGINEERING MECHANICSENGINEERING MECHANICS--STATICS by R.C. HIBBELER, PRENTICE HALLby HALL

2. LECTURE NO. 1LECTURE 1INTRODUCTION, SCALARS & VECTORSINTRODUCTION, VECTORS Objectives:►To explain the basic definitions of engineering mechanicsmechanics ►To define scalars and vectorsscalars vectors ►To explain vector operationsvector operations, such as:, as: ƒƒMultiplication and division of a vector by a scalarscalar ƒƒVector additionVector addition ƒƒVector subtractionVector subtraction ƒƒResolution of vectorResolution vector

3. Definitions Definitions:
Mechanics:It is the branch of physics dealing with state of
bodies under the influence of forces.
Statics:It is the branch of mechanics dealing with rigid bodies at rest or those moving at a constant velocity.
Dynamics:It is the branch of mechanics dealing with rigid
bodies at motion (acceleration).

4. PHYSICS MECHANICSDEFORMABLEBODIESRIGIDBODIESFLUIDSSTATICS(CE 201) DYNAMICS(ME 201)

5. SCALARS AND VECTORS Scalar QuantitiesScalar Quantities ••A scalarA scalaris a quantity that is has only magnitudehas magnitude, either positive or negative.••For example, mass, volume, and lengthmass, lengthare the scalar are quantities often used in statics.••Scalars are indicated by letters in italic type, such as the scalar ‘‘AA’’..

6. SCALARS AND VECTORS Vector QuantitiesVector Quantities••A vectorA vectoris a quantity that is has both a magnitude and a direction.••For example, position, force, and momentposition, momentare the are vector quantities frequently encountered in statics.••Vectors are indicated by bold lettersindicated letters, such as the , vector ‘‘AA’’oror••The magnitude of a vector is always a positive quantityquantityand is symbolized in italic type, and written as or AA AJG

7. ƒƒA vector is represented graphically by an arrowrepresented arrow, , which is used to define itswhich its ►magnitude ((by the lengthlengthof the arrowof arrow)) ►directiondirection((by the angleanglebetween a reference axis and between the arrowthe arrow’’s line of actions action)) ►sensesense((by the arrowheadarrowhead)) For exampleexample, the vector shown below has, has•A magnitude= 4 units•Adirection= 20°, measured counterclockwise from the horizontal axis•A sensewhich is upward and to the right•Point O is called tailof the vector•Point P is called tip or headof the vectorSCALARS AND VECTORS Vector Quantities----contd.

8. VECTOR OPERATIONS Multiplication and Division of a Vector by a ScalarMultiplication Scalar••The product of a vector AAand a scalar and aa= a AA••Magnitude of the product vector = ||a A|••Sense of the product vector a AAwill be the same will if aais positiveis positive••Sense of the product vector a AAwill be opposite will if aais negativeis negative

9. VECTOR OPERATIONS Multiplication and Division of a Vector by a ScalarMultiplication Scalar------ Graphic examples of multiplication and division of a vector AAare shown in the following Figures:are

10. Two vectors AAand and B may be added to form a resultant vector RR= = AA+ + BBusing the following methods:using ►Parallelogram lawParallelogram law ►Triangle constructionTriangle constructionTwo given vectorsVECTOR OPERATIONSVector Addition
or

11. VECTOR OPERATIONSVECTOR OPERATIONSVector SubtractionVector Subtraction ƒƒVectors AAand and BBmay be subtracted to form a resultant may vector RR′′= = AA––BB= = AA+ (+ (––BB)) using the following methods:►Parallelogram lawParallelogram law ►Triangle constructionTriangle construction Triangularconstruction Two givenvectors Parallelogramlaw

12. VECTOR OPERATIONSVECTOR OPERATIONSResolution of VectorResolution Vector ƒƒA vector may be resolved into two components having known lines of action by using the parallelogram law.ƒƒFor example, a vector RRmay be resolved into two vectors may AAand and BBalong the lines a and b, using the parallelogram law, as along shown below:

13. Multiple Choice Problems
1.The material properties of a body may be neglected by
(a)Particle idealization
(b)Rigid body idealization
(c) Concentrated force idealization
(d) None of the above

14. Multiple Choice Problems
2.According to the Particle idealizationof a body,
----------may be neglected
(a) area over which the load is applied
(b) geometry of the body
(c) material properties of the body
(d) None of the above

15. Multiple Choice Problems
3.Multiplication of a vector by a scalar will never change the vector’s
(a) magnitude
(b) sense
(c) direction