1. Engineering Mechanics

2. What is Mechanics ?
Mechanics is a science that describes or predicts the conditions of rest or motion of bodies under the action of forces.

3. History Aristotle ( 384 -322 B.C.) Archimedes ( 287 – 212 B.C.)
Isaac Newton ( 1642 – 1727)
D’Lambert
Lagrange
Hamilton
Albert Einstein ( Theory of Relativity )

4. Unit of length is meter (m)
Basic Concepts
Space : 3 dimensional
Position of point A is defined by three lengths measured from the origin in three directions. (coordinates) o
Unit of length is meter (m) A

5. Basic Concepts Mass : Unit of mass is kilogram (kg) Force :
a fundamental property of a body
amount of matter in the body
a numerical measure of its inertia
Force :
the action of a body on another body
it causes the body to accelerate, that is to change its velocity
It can be applied by actual contact or at a distance (gravitational forces, magnetic forces)
Unit of mass is
kilogram (kg)

6. Basic Concepts Force : Unit of force is newton (N) Defined by a vector
Force is defined by :
its point of application
its magnitude
its direction
Unit of force is
newton (N)
30°
Defined by a vector A

7. Basic Concepts Resultant Force :
The total effect of two or more forces acting on a particle or a body can be represented by a single force which is called resultant force. P R A Q

8. combination of a large number of particles
Basic Concepts
Particle :
very small amount of matter which may be assumed to occupy a single point in a space
Rigid Body :
combination of a large number of particles

9. Basic Concepts Newton’s Three Fundamental Laws:
If the resultant force on a particle is zero, then:
a. if it was at rest originally , it remains at rest
b. if it was in motion, its velocity doesn’t change

10. Newton’s Three Fundamental Laws:
Basic Concepts
Newton’s Three Fundamental Laws:
2. If the resultant force is not zero, then it causes the particle or the body to have an acceleration.
The amount of the acceleration is proportional to the magnitude of the resultant and in the direction of the resultant force
F = m a
F = resultant force acting on the particle
m = mass of the particle
a = acceleration of the particle

11. Basic Concepts (Reminder)
Speed
Speed is the rate at which a particle changes its position
The distance taken in unit time (meters/second)
It refers to how fast a particle is moving
It is a scalar quantity.
Direction doesn’t matter
Velocity
Speed with defined direction
Vector quantity

12. Basic Concepts (Reminder)
Acceleration
the rate of change in velocity
It refers to how fast a particle changes its velocity
amount of change in velocity in unit time
(meters/second) / second = meters/ second squared) =

13. Newton’s Three Fundamental Laws:
Basic Concepts
Newton’s Three Fundamental Laws:
3. The forces of action and reaction between bodies in relation have the same magnitude, same line of action but opposite direction.

14. Newton’s Law of Gravitation:
Basic Concepts
Newton’s Law of Gravitation: m -F
m,M : masses of particles
r : distance between particles F M r
Two particles (bodies) attract each other mutually with equal and opposite forces F and –F of magnitude F
G : universal constant

15. Newton’s Law of Gravitation:
Basic Concepts
Newton’s Law of Gravitation:
Special Case
Attraction of earth on a particle located on its surface
R : the radius of earth,
M: mass of earth

16. Newton’s Law of Gravitation:
Basic Concepts
Newton’s Law of Gravitation:
Special Case
Weight : W
the gravitational force applied on particle by the earth

17. Systems Of Units Time : second (s)
Original definition : 1 / of mean solar day
Official definition : 9,192,631,770 cycles of the radiation corresponding to the transition between two levels of the fundamental state of cesium-133 atom.
Length : meter (m)
Original definition : 1 / 10,000,000 of the distance from equator to either pole
Official definition : 1,650, wavelengths of the orange-red light corresponding to a certain transition in a atom of krypton-86

18. Systems Of Units Mass : kilogram (kg)
Original definition : mass of 0,001 m3 water
Official definition : mass of platinum-iridium standart
Force : newton (N)
The magnitude of force that gives an acceleration of to a mass of 1 kg.
1 N = (1 kg) ( )

19. Systems Of Units Weight : Newton (N)
the gravitational force applied on a body by the earth
m : the mass of particle ( kg)
The weight of a body of mass 1 kg :

20. Review the other systems of units
Homework
Review the other systems of units
Units of Area
Units of Volume
etc