introduction to engineering mechanics
TRANSCRIPT
Introduction to
APPLIED MECHANIC
Sby
RAMESH CH. PANDA
APME101: APPLIED MECHANICS
L: 4 T: 0 P: 2
Course Objective:•To make the awareness to the
students about the basic concepts of mechanics
•To understand examines the response of bodies or systems of bodies to external forces
To bridges the gap between physical theory and its application to technology.
Introduction: Concept and Definition of Engineering Mechanics, Types of Mechanics, Application of engineering mechanics in practical fields. Definition of Applied Mechanics. Definition, basic quantities and derived quantities of basic units and derived units. Different systems of units (FPS, CGS, MKS and SI) and their conversion from one system to another system. Concept of rigid body, scalar and vector quantities.
Laws of Forces: Definition, measurement, representation, types of forces, effects and characteristics of a force. Different force systems (coplanar and non-coplanar), principle of transmissibility of forces, law of super-position. Composition and resolution of coplanar concurrent forces, resultant force, laws of forces-Triangle law of forces, Polygon law of forces, Parallelogram law of forces. Free body diagrams, concept of Lami’s Theorem.
Friction: Definition and concept of friction, types of friction, force of friction. Laws of static friction, coefficient of friction, angle of friction, angle of repose, cone of friction. Equilibrium of a body lying on a horizontal plane and rough inclined plane. Calculation of least force required to maintain equilibrium of a body on a rough inclined plane subjected to a force: a) Acting along the inclined plane horizontally b) At some angle with the inclined plane.
Moment: Concept of moment, Varignon’s theorem. Principle of moments - application of moments to simple mechanisms, parallel forces-like and unlike parallel forces, calculation of their resultant, concept of couple, properties and effect, general cases of coplanar force system, general conditions of equilibrium of bodies under coplanar forces.
Center of Gravity: Concept of gravity, gravitational force, centroid and centre of gravity. Centroid for regular lamina and centre of gravity for regular solids. Position of centre of gravity of compound bodies and centroid of composite area. CG of bodies with portions removed.
Moment of Inertia: Concept of moment of inertia and second moment of area and radius of gyration, theorems of parallel and perpendicular axis, second moment of area of common geometrical sections: rectangle, triangle, circle. Second moment of area for L, T and I sections, section modulus.
Simple Machine: Concept of machine, mechanical advantage, velocity ratio and efficiency of a machine, their relationship, law of machine, simple machines (lever, wheel and axle, pulleys, jack winch crab inclined plane, worm and worm wheel only) ideal machine and effect of friction in machines.
Science ?
sciencemay be defined as the growth
of ideas through observation and experimentation
Applied Science?
The branch of science, which co ordinates the research work, for practical utility and services of the mankind, is known as Applied Science.
Engineering?
Engineering is the application of mathematics, empirical evidence and scientific, economic, social, and practical knowledge in order to invent, innovate, design, build, maintain, research, and improve structures, machines, tools, systems, components, materials, processes and organizations.
Mechanics?
The branch of applied physics dealing with motion and forces
producing motion.OR
Mechanics is the science which describes and predicts the
conditions of rest or motion of bodies under the action of forces
mechanicsMechanics is an area of science
concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment.
Applied mechanics ?
Applied mechanics is a branch of the physical sciences and the practical application of mechanics. Applied mechanics describes the response of bodies (solids and fluids) or systems of bodies to external forces.
STATICS
It is that branch of Engineering Mechanics, which deals with the forces and their effects, while acting upon the bodies at rest.
DYNAMICS
It is that branch of Engineering Mechanics, which deals with the forces and their effects, whileacting upon the bodies in motion.
The subject of Dynamics may be further sub-divided into the
following two branches :1. Kinetics, and 2. Kinematics.
KINETICS
It is the branch of Dynamics, which deals with the bodies in motion due to the applicationof forces.
KINEMATICS It is that branch of Dynamics,
which deals with the bodies in motion, without any reference to the forces which are responsible for the motion.
Eng. Malek AbuwardaLecture 1 Engineering Mechanics – Statics23
Basic Terms Essential basic terms to be understood
Rigid body: the relative movement between its parts are negligibleDynamics: dealing with a rigid-body in motionLength: applied to the linear dimension of a strait line or curved lineArea: the two dimensional size of shape or surfaceVolume: the three dimensional size of the space occupied by substance
Force: the action of one body on another whether it’s a push or a pull force
Mass: the amount of matter in a body
Weight: the force with which a body is attracted toward the centre of the Earth
Particle: a body of negligible dimension
© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
Triangle Law of Vectors
• Triangle Law of Vectors states that if two vectors are represented as adjacent sides of a triangle then the third side taken in opposite order is the resultant of the two. This law is used to find the resultant of two vector which gives both magnitude and direction
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
newton's second law of motion
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
newton's third law of motion
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
newton's third law of gravity
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© 2007 The McGraw-Hill Companies, Inc. All rights reserved.
Vector Mechanics for Engineers: Statics
EighthEdition
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Free-Body Diagrams:• Free-Body Diagrams:
Create separate diagrams for each of the bodies involved with a clear indication of all forces acting on each body.
•
Major topics of applied mechanics
Archimedes of Syracuse
Omar Khayyám
Galileo Galilei
Johannes Kepler
Isaac Newton
Classification of mechanics
1. Classical mechanics2. Quantum mechanics
Classical mechanicsNewtonian mechanics- theory of motion
Analytical mechanics- system energyHamiltonian- mechanics-conservation of energy
Lagrangian mechanics- principle of the least action.
Classical statistical mechanics-thermodynamic
Celestial mechanics- galaxies
Astrodynamics-spacecraft
Solid mechanics elasticity
Classical mechanics Acoustics Statics Fluid mechanics, Soil mechanics Continuum mechanics Hydraulics Fluid statics, Applied mechanics or Engineering
mechanics Biomechanics
Classical mechanicsBiophysicsRelativistic/ Einsteinian mechanics
Quantum mechanics Schrödinger wave mechanics-wavefunction of a
single particle
Matrix mechanics-finite-dimensional state space
Quantum statistical mechanics-Particle physics-Nuclear physicsCondensed matter physics
UNITS1. FUNDAMENTAL UNITS2. DERIVED UNITS
FUNDAMENTAL UNITS
DERIVED UNITS
SYSTEMS OF UNITS1. C.G.S. units -Centimetre–gram–second
system of units 2. F.P.S. units -Foot–pound–second system
3. M.K.S. units- metre, kilogram, and/or second
4. S.I. units (INTERNATIONAL SYSTEM OF UNITS)
S.I. units (INTERNATIONAL SYSTEM OF UNITS)
a system of physical units ( SI units ) based on the metre, kilogram, second, ampere, kelvin, candela, and mole, together with a set of prefixes to indicate multiplication or division by a power of ten.
S.I. UNITS (INTERNATIONAL SYSTEM
OF UNITS)
Dimensions500.101 SI Primitives
DIMENSION UNIT SYMBOL for UNIT
Length meter m
Mass kilogram kg
Time second s
Elec. Current ampere A
luminous intensity candela cd
amount of substance mole mol
Dimensions500.101 SI Derived units
DESCRIPTION DERIVED UNIT SYMBOL DIMENSION
Force newton N mkg/s2
Energy joule J m2kg/s2
Pressure pascal Pa kg/(ms2)
Power watt W m2kg/s3
SI Unit Prefixes - Part IName Symbol Factor
tera- T 1012
giga- G 109
mega- M 106
kilo- k 103
hecto- h 102
deka- da 101
SI Unit Prefixes- Part II
Name Symbol Factordeci- d 10-1
centi- c 10-2
milli- m 10-3
micro- μ 10-6
nano- n 10-9
pico- p 10-12
femto- f 10-15
The Seven Base SI UnitsQuantity Unit SymbolLength meter mMass kilogram kgTemperature kelvin KTime second sAmount of Substance
mole mol
Luminous Intensity candela cdElectric Current ampere a
Derived SI Units (examples)Quantity unit Symbol
Volume cubic meter m3
Density kilograms per cubic meter
kg/m3
Speed meter per second m/s
Newton kg m/ s2 N
Energy Joule (kg m2/s2) J
Pressure Pascal (kg/(ms2) Pa
Scientific Notation
M x 10n
• M is the coefficient • 10 is the base• n is the exponent or power of 10
Factor-Label Method of Unit Conversion
• Example: Convert 5km to m:• Multiply the original measurement by a
conversion factor.
NEW UNIT85km x 1,000m = 85,000m
1km OLD UNIT
Factor-Label Method of Unit Conversion: Example
• Example: Convert 789m to km:
789m x 1km =0.789km= 7.89x10-1km
1000m
Convert 75.00 km/h to m/s 75.00 km x 1000 m x 1 h___ = 20.83m/s h 1 km 3600 s
Standard prefixes for the SI units of measure
USEFUL DATA
TRIGONOMETRY
RULES FOR S.I. UNITS
standard abberviations
TRIGONOMETRY
INTEGRAL CALCULUS
SCALAR QUANTITIESThe scalar quantities (or
sometimes known as scalars) are those quantities which have magnitude
only such as length, mass, time, distance, volume, density, temperature, speed etc.
VECTOR QUANTITIES
1. Unit vector. A vector, whose magnitude is unity,is known as unit vector.
2. Equal vectors. The vectors, which are parallel to each other and have same direction (i.e.,
same sense) and equal magnitude are known as equal vectors. 3. Like vectors. The vectors, which are parallel to each other and have
same sense but unequal magnitude, are known as like vectors.
Example 1Two forces of 100 N and 150 N are
acting simultaneously at a point. What is the resultant of these two forces, if the angle between them is 45°?
Example 2.
Two forces act at an angle of 120°. The bigger force is of 40 N and theresultant is perpendicular to the smaller one. Find the smaller force.