Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-1 EML 3004C CHAPTER ONE General Principles

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-2 EML 3004C Statics, Dynamics and Mechanics of Materials  Statics deals with the state of rest or motion of bodies with constant velocities  In dynamics, the bodies are allowed to accelerate.  Two Branches of static equilibrium Statics Mechanics of Materials  Statics Equilibrium of Bodies-material independent, uses only static equations  Mechanics of Materials Relationship between the external loads, the intensity of internal forces and its deformation response

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-3 EML 3004C Basic Concepts  Quantities Length (location, position, size) Time (succession of events) Force (Push, Pull) Mass (Properties of Matter) ONLY THREE OF FOUR NEEDED (NEWTONS LAW)  Idealization Particle (neglect, size, geometry) Rigid Body (all points within remain in the same position, at fixed distances from each other) Concentrated Force ( over a very small area, zero)

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-4 EML 3004C Physical Quantities  Physical Qualities Mass, Force time distance, Density Temperature Volume area length displacement velocity acceleration

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-5 EML 3004C  Scalar Quantities Described by their magnitude, mass (italic form) or lower case (a for A)  Vector Quantities Described by a magnitude, a direction, and a point of application (Bold Face) in the book Bar or Arrow in handwritten work Magnitude or A (italic) or a = Scalar and Vector Quantities R R

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-6 EML 3004C Newton’s Laws  Newton’s First Law A body at rest tends to remain at rest & a body in motion at a constant velocity will tend to maintain the velocity.  Newton’s Second Law Change of motion is proportional to the moving force impressed and takes place in the direction of the straight line in which such force is impressed.

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-7 EML 3004C Newton’s Laws  Consequences of Newton’s Third Law When two bodies interact, a pair of equal and opposite reaction forces will exist at their contact point. This force pair will have the same magnitude and acts along the same direction, but have opposite sense. The mutual force of action and reaction between two bodies are equal, opposite, and collinear. Kg = mass=[m] Newton = Force=[F] Slug= mass =[m] lbf = Force = [F]

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-8 EML 3004C  Gravitational Law G = universal constant of gravitation m 1,m 2 = mass of each of the two particles r= distance Gravitational Law

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-9 EML 3004C  Weight If = mass of the particle = mass of the earth r = distance of the particle to the earth’s center W = weight of the particle if What is weight?

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-10 EML 3004C  SI (International System of Units) Meter (m) Second (sec) Kilogram (kg) Newton (N) Units  Units Length, time, mass, force - basic quantities (Note: we use bars to denote forces or vectors) W = 9.81N Ex : mass = 1kg

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-11 EML 3004C Conversion of Units  Conversion of Units FPSSI Force1 lb= N Mass1 slug = kg Length1 ft= m Ex:

Namas Chandra Introduction to Mechanical engineering Hibbler Chapter 1-12 EML 3004C CHAPTER ONE.. concludes General Principles