LECTURE 1 Introduction to Statics
Transcript of LECTURE 1 Introduction to Statics
![Page 1: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/1.jpg)
LECTURE 1
Introduction to Statics
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
![Page 2: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/2.jpg)
WHAT AND WHY STUDY STATICS ??
Mechanics can be divided into 3 branches:- Rigid-body Mechanics
- Deformable-body Mechanics- Fluid Mechanics
Rigid-body Mechanics deals with
- Statics - Dynamics
Statics is actually the application of mathematics and basic physics (Newton’s laws) to study forces in materials, machines and structures. Forces are of interest to engineers for two reasons:
1. they cause materials to deform and break, and2. they cause things to move.
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
![Page 3: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/3.jpg)
� Statics is used to calculate forces in systems that don’t move, or move at constant velocity. The application of physics to study motion is known as dynamics.
Structural engineers – Design buildings and structures,Mechanical engineers – Design machinery, which may range from engines to micro electro-mechanical systems.Biomedical engineers – Design artificial organs and implants.
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
![Page 4: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/4.jpg)
Fundamental concepts
Basic Quantities
Length – Locate position and describe size of physical system.Define distance and geometric properties of a body
Mass – Comparison of action of one body against anotherMeasure of resistance of matter to a change in velocity
Time – Conceive as succession of events
Force – “push” or “pull” exerted by one body on another– Occur due to direct contact between bodies e.g. – Person pushing against the wall– Occur through a distance without direct contact e.g. – Gravitational, electrical and magnetic forces
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
![Page 5: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/5.jpg)
Fundamental concepts
Idealizations
� Particles – Consider mass but neglect size
E.g.: Size of Earth insignificant compared to its size of orbit
� Rigid Body – Combination of large number of particles
– Neglect material properties
E.g.: Deformations in structures, machines and mechanism
� Concentrated Force – Effect of loading, assumed to act at a point on a body
– Represented by a concentrated force, provided loading area is small compared to overall size
E.g.: Contact force between wheel and ground
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
![Page 6: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/6.jpg)
Newton’s Three Laws of Motion
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
“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”
Newton’s First Law
![Page 7: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/7.jpg)
Newton’s 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”
maF =
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
![Page 8: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/8.jpg)
“The mutual forces of action and reaction between two particles are equal
and, opposite and collinear”
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
Newton’s Third Law
![Page 9: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/9.jpg)
Newton’s Law of Gravitational Attraction
F = force of gravitation between two particles
G = universal constant of gravitation
m1,m2 = mass of each of the two particles
r = distance between the two particles
221
r
mmGF =
Weight,
Letting yields
2r
mMGW e=
2/ rGMg e= mgW =
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
![Page 10: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/10.jpg)
Comparing F = mg with F = ma
� g is the acceleration due to gravity
� Since g is dependent on r, weight of a body is not an absolute quantity
� Magnitude is determined from where the measurement is taken
� For most engineering calculations, g is determined at sea level and at a
latitude of 45°
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
![Page 11: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/11.jpg)
Units of Measurement
Name Length Time Mass Force
International Systems of Units (SI)
Meter (m)
Second (s)
Kilogram (kg)
Newton (N)
SI Units
Système International d’Unités
• F = ma is maintained only if – Three of the units, called base units, are arbitrarily defined– Fourth unit is derived from the equation
• SI system specifies length in meters (m), time in seconds (s) and mass in kilograms (kg)
• Unit of force, called Newton (N) is derived from F = ma
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
![Page 12: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/12.jpg)
Units of Measurement
At the standard location,
g = 9.806 65 m/s2
� For calculations, we use
g = 9.81 m/s2
Thus,
W = mg (g = 9.81m/s2)
Hence, a body of mass 1 kg has a weight of 9.81 N,
a 2 kg body weighs 19.62 N
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN
![Page 13: LECTURE 1 Introduction to Statics](https://reader030.fdocuments.us/reader030/viewer/2022020620/61e36a6f063615715170ab99/html5/thumbnails/13.jpg)
Prefixes
� For a very large or very small numerical quantity, the units can be modified by using a prefix. Each represent a multiple or sub-multiple of a unit
E.g.: 4,000,000 N = 4000 kN (kilo-newton)
= 4 MN (mega- newton)
0.005m = 5 mm (mili-meter)
Exponential Form
Prefix SI Symbol
Multiple
1 000 000 000 109 Giga G
1 000 000 106 Mega M
1 000 103 Kilo k
Sub-Multiple
0.001 10-3 Milli m
0.000 001 10-6 Micro μ
0.000 000 001 10-9 nano n
PROF. DR. SHAHRUDDIN BIN MAHZAN@MOHD ZIN