ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at School of Bioprocess Engineering, UniMAP

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at Course Content Static This course covers vector representation of forces, moments and couples of static equilibrium of particles, rigid bodies, and engineering structures, together with analysis of external and internal forces in structures via the methods of free- body diagrams and properties of cross-sectional areas. Dynamic In addition, the course also elaborates on kinematics and kinetics of system of particles and of rigid bodies in two and three-dimensional spaces covering force and acceleration, linear and angular momentum, and energy conservation.

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at Course Outcomes Ability to apply the basic principles of statics and dynamics on mechanism and bodies. Ability to analyze systems/problems related to forces, loads, displacement for bodies at rest. Ability to analyze systems/problems related to forces, loads, displacement, velocity and acceleration of bodies in motion.

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at Evaluation Peperiksaan/ Examination: 70% Mid Term Examination 1 = 10% Mid Term Examination 2 = 10% Final Examination = 60% (ii) Kerja kursus/course work: 20% Assignment/Quiz = 20%

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at Text Book

Chapter 1 Introduction & General Principles

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at World highest building Burj Dubai 828 m Taipei m KLCC 442 m Shanghai World Financial Center 492 m International Commerce Centre (Hong Kong, China) 483m

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.1 Mechanics Mechanics can be divided into 3 branches: - Rigid-body Mechanics - Deformable-body Mechanics - Fluid Mechanics (2nd year) Rigid-body Mechanics deals with - Statics - Dynamics

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.1 Mechanics Statics – Equilibrium of bodies  At rest  Move with constant velocity Dynamics – Accelerated motion of bodies

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.2 Fundamentals Concepts Basic Quantities 1. Length - locate the position of a point in space 2. Mass - measure of a quantity of matter 3. Time - succession of events 4. Force - a “push” or “pull” exerted by one body on another

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.2 Fundamentals Concepts Idealizations 1. Particles - has a mass and size can be neglected 2. Rigid Body - a combination of a large number of particles 3. Concentrated Force - the effect of a loading

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.2 Fundamentals Concepts Newton ’ s Three Laws of Motion First Law “ A particle originally at rest, or moving in a straight line with constant velocity, will remain in this state provided that the particle is not subjected to an unbalanced force ”

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.2 Fundamentals Concepts Newton ’ s Three Laws of Motion Second Law “ A particle acted upon by an unbalanced force F experiences an acceleration a that has the same direction as the force and a magnitude that is directly proportional to the force ”

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.2 Fundamentals Concepts Newton ’ s Three Laws of Motion Third Law “ The mutual forces of action and reaction between two particles are equal and, opposite and collinear ”

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.2 Fundamentals Concepts Newton ’ s Law of Gravitational Attraction Weight: Letting yields F = force of gravitation between two particles G = universal constant of gravitation m 1,m 2 = mass of each of the two particles r = distance between the two particles

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.3 Units of Measurement SI Units Stands for Système International d’Unités F = ma is maintained only if – 3 of the units, called base units, are defined – 4 th unit is derived from the equation SI system specifies length in meters (m), time in seconds (s) and mass in kilograms (kg) Force unit, Newton (N), is derived from F = ma

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.3 Units of Measurement NameLengthTimeMassForce International Systems of Units (SI) Meter (m) Second (s) Kilogram (kg) Newton (N)

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.3 Units of Measurement At the standard location, g = m/s 2 For calculations, we use g = 9.81 m/s 2 Thus, W = mg (g = 9.81m/s 2 ) Hence, a body of mass 1 kg has a weight of 9.81 N, a 2 kg body weighs N

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.4 The International System of Units Prefixes For a very large or small numerical quantity, units can be modified by using a prefix Each represent a multiple or sub-multiple of a unit Eg: 4,000,000 N = 4000 kN (kilo-newton) = 4 MN (mega- newton) 0.005m = 5 mm (milli-meter)

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.4 The International System of Units

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.5 Numerical Calculations Dimensional Homogeneity Each term must be expressed in the same units Regardless of how the equation is evaluated, it maintains its dimensional homogeneity All terms can be replaced by a consistent set of units

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.5 Numerical Calculations Significant Figures Accuracy of a number is specified by the number of significant figures it contains A significant figure is any digit including zero e.g and have four significant numbers When numbers begin or end with zero, we make use of prefixes to clarify the number of significant figures e.g. 400 as one significant figure would be 0.4(10 3 )

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.5 Numerical Calculations Rounding Off Numbers Accuracy obtained would never be better than the accuracy of the problem data Calculators or computers involve more figures in the answer than the number of significant figures in the data Calculated results should always be “ rounded off ” to an appropriate number of significant figures

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.5 Numerical Calculations Calculations Retain a greater number of digits for accuracy Work out computations so that numbers that are approximately equal Round off final answers to three significant figures

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at 1.6 General Procedure for Analysis To solve problems, it is important to present work in a logical and orderly way as suggested: 1. Correlate actual physical situation with theory 2. Draw any diagrams and tabulate the problem data 3. Apply principles in mathematics forms 4. Solve equations which are dimensionally homogenous 5. Report the answer with significance figures 6. Technical judgment and common sense

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at Example Convert to 2 km/h to m/s. Solution Remember to round off the final answer to three significant figures.

ERT 146 Engineering Mechanics Ms Siti Kamariah Md Sa’at