Engineering Mechanics diploma-Module-1.pptx

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1. 1 Module-1: Introduction to engineering mechanics Learning outcomes: Describe what makes engineering different from science course overview Identify the systems of units used in the course Classification of mechanics Scalars and Vectors Principles of engineering mechanics

2. 2 “The scientist discover the world that exists. The engineer creates what never was.” An  engineer  uses scientific principles to design and operate equipment, to move and interact materials Scientist vs Engineer

3. 3 course overview

4. 4 Identify the systems of units used in the course Parameter SI (metric) Distance Meters (m) Velocity Meters/sec (m/s) Acceleration Meters/sec 2 (m/s 2 ) Mass Kilogram (kg) Force Newton (N) = kg*m/s 2 Energy Joules (J) = N-m Multiplier Prefix Symbol 10 9 giga G 10 6 mega M 10 3 Kilo K 10 -2 Centi c 10 -3 milli m 10 -6 micro μ 10 -9 nano n 10 -12 pico p

5. 5 Classification of mechanics “Mechanics can be defined as that science which describes and predicts the condition of rest or motion of bodies under the action of forces”

6. 6 Scalars and Vectors Scalar Quantity Has magnitude Has no associated direction Examples: Volume Time Mass distance Speed Density Temperature Vector Quantity Has magnitude Has direction Examples: Moment Displacement Velocity Acceleration Force

7. 7 Distance vs Displacement: Suppose you are observing an ant on the table, as shown in the diagram below. The ant moves from one corner of the table to the other corner. The blue irregular line shows the path of the ant (distance) and green straight line is the shortest path (displacement). Scalars and Vectors

8. 8 Principles of engineering mechanics Sir Isaac Newton - 25 December 1642 – 20 March 1727 was an English physicist and mathematician (described in his own day as a "natural philosopher") who is widely recognised as one of the most influential scientists of all time and as a key figure in the scientific revolution.

9. 9 Principles of engineering mechanics Newton’s first law: “An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This law is often called the law of inertia.” Example :The motion of a kite when the wind changes can also be described by the first law

10. 10 Principles of engineering mechanics Newton’s second law: The rate of change of momentum is directly proportional to impressed force and it takes place in the direction of force acting on it”. Force ∝ rate of change of momentum. But momentum = mass × velocity As mass do not change Force ∝ mass × rate of change of velocity i.e., Force ∝ mass × acceleration F ∝ m × a

11. 11 Principles of engineering mechanics Newtons’s third law: “For every action there is an equal and opposite reaction”.

12. 12 Principles of engineering mechanics Newton’s law of gravitation: “Everybody attracts the other body. The force of attraction between any two bodies is directly proportional to their masses and inversely proportional to the square of the distance between them” Where G=6.67*10 -11 N-m 2 /kg 2

13. 13 Principles of engineering mechanics Principle of transmissibility: “The state of rest or of Uniform motion of a rigid body is unaltered if the point of application of the force is transmitted to any other point along the line of action of the force”.

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