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  • COURSE:COURSE: CE 201 (STATICS)CE 201 (STATICS)

    LECTURE NO.:LECTURE NO.: 0101

    FACULTY:FACULTY: DR. SHAMSHAD AHMADDR. SHAMSHAD AHMAD

    DEPARTMENT:DEPARTMENT: CIVIL ENGINEERINGCIVIL ENGINEERING

    UNIVERSITY:UNIVERSITY: KING FAHD UNIVERSITY OF PETROLEUM KING FAHD UNIVERSITY OF PETROLEUM & MINERALS, DHAHRAN, SAUDI ARABIA& MINERALS, DHAHRAN, SAUDI ARABIA

    TEXT BOOK:TEXT BOOK: ENGINEERING MECHANICSENGINEERING MECHANICS--STATICS STATICS by R.C. HIBBELER, PRENTICE HALLby R.C. HIBBELER, PRENTICE HALL

  • LECTURE NO. 1LECTURE NO. 1INTRODUCTION, SCALARS & VECTORSINTRODUCTION, SCALARS & VECTORS

    Objectives:Objectives: To explain the To explain the basic definitions basic definitions of engineering of engineering

    mechanicsmechanics To define To define scalars and vectorsscalars and vectors To explain To explain vector operationsvector operations, such as:, such as: Multiplication and division of a vector by a Multiplication and division of a vector by a

    scalarscalar Vector additionVector addition Vector subtractionVector subtraction Resolution of vectorResolution of vector

  • DefinitionsDefinitions::

    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).

  • PHYSICS

    MECHANICS

    DEFORMABLEBODIES

    RIGIDBODIES

    FLUIDS

    STATICS(CE 201)

    DYNAMICS(ME 201)

  • SCALARS AND VECTORS SCALARS AND VECTORS Scalar QuantitiesScalar Quantities

    A scalarA scalar is a quantity that is a quantity that has only magnitudehas only magnitude, either , either positive or negative.positive or negative.

    For example, For example, mass, volume, and lengthmass, volume, and length are the scalar are the scalar quantities often used in statics.quantities often used in statics.

    Scalars are indicated by letters in italic type, such as Scalars are indicated by letters in italic type, such as the scalar the scalar AA..

  • SCALARS AND VECTORS SCALARS AND VECTORS Vector QuantitiesVector Quantities

    A vectorA vector is a quantity that is a quantity that has has both a magnitude and a both a magnitude and a direction.direction.

    For example, For example, position, force, and momentposition, force, and moment are the are the vector quantities frequently encountered in statics.vector quantities frequently encountered in statics.

    Vectors are Vectors are indicated by bold lettersindicated by bold letters, such as the , such as the vector vector AA oror

    The The magnitude of a vector is always a positive magnitude of a vector is always a positive quantityquantity and is symbolized in italic type, and is symbolized in italic type, written as or written as or AA

    AJG

  • A vector is A vector is represented graphically by an arrowrepresented graphically by an arrow, , which is used to define itswhich is used to define its magnitude magnitude ((by the by the lengthlength of the arrowof the arrow)) directiondirection ((by the by the angleangle between a reference axis and between a reference axis and

    the arrowthe arrows line of actions line of action)) sensesense ((by the by the arrowheadarrowhead))

    For For exampleexample, the vector shown below has, the vector shown below has A magnitude = 4 units A direction = 20, measured counterclockwise

    from the horizontal axis A sense which is upward and to the right Point O is called tail of the vector

    Point P is called tip or head of the vector

    SCALARS AND VECTORS Vector Quantities----contd.

  • VECTOR OPERATIONS VECTOR OPERATIONS Multiplication and Division of a Vector by a ScalarMultiplication and Division of a Vector by a Scalar

    The product of a vector The product of a vector AA and a scalar and a scalar aa = = a a AA

    Magnitude of the product vector = Magnitude of the product vector = ||a a A|A|

    Sense of the product vector Sense of the product vector a a AA will be the same will be the same if if aa is positiveis positive

    Sense of the product vector Sense of the product vector a a AA will be opposite will be opposite if if aa is negativeis negative

  • VECTOR OPERATIONS VECTOR OPERATIONS Multiplication and Division of a Vector by a ScalarMultiplication and Division of a Vector by a Scalar------

    Graphic examples of multiplication and division of a Graphic examples of multiplication and division of a vector vector AA are shown in the following Figures:are shown in the following Figures:

  • Two vectors Two vectors AA and and B B may be added to form a resultant may be added to form a resultant vector vector

    RR = = AA + + BBusing the following methods:using the following methods: Parallelogram lawParallelogram law Triangle constructionTriangle construction

    Two given vectors

    VECTOR OPERATIONSVector Addition

    or

  • VECTOR OPERATIONSVECTOR OPERATIONSVector SubtractionVector Subtraction

    Vectors Vectors AA and and BB may be subtracted to form a resultant may be subtracted to form a resultant vector vector

    RR = = AA BB = = AA + (+ ( BB))using the following methods:using the following methods:Parallelogram lawParallelogram lawTriangle constructionTriangle construction

    Triangularconstruction

    Two givenvectors

    Parallelogramlaw

  • VECTOR OPERATIONSVECTOR OPERATIONSResolution of VectorResolution of Vector

    A vector may be resolved into two components having known A vector may be resolved into two components having known lines of action by using the parallelogram law.lines of action by using the parallelogram law.

    For example, a vector For example, a vector RR may be resolved into two vectors may be resolved into two vectors AAand and BB along the lines a and b, using the parallelogram law, as along the lines a and b, using the parallelogram law, as

    shown below:shown below:

  • 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

  • Multiple Choice Problems

    2. According to the Particle idealization of 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

  • Multiple Choice Problems

    3. Multiplication of a vector by a scalar will never change the vectors

    (a) magnitude

    (b) sense

    (c) direction