Ahmadi khan

1. Lecture 02
BY
Engr Muhammad Usman
Mechanical Engineering
Department
CECOS University

2. COURSE OUTLINE
• Fundamental concept and principle of
mechanics, important vector quantity
• Force system i.e concurrent
• Non concurrent and parallel force system
• Resultant of forces
• Moment and couple
• Equilibrium of forces (law & type) concept of
free body diagram

3. Force
• Is the action of one body on another.
• A force is characterized by its point of
application, magnitude, and direction.
• Force is a vector quantity.
• We can separate the action of a force into two
effect , External and Internal.

4. Principle of Transmissibility
The principle of transmissibility states that a force may be
applied at any point on its given line of action without altering
the resultant effects of the force external to the rigid body on
which it acts.
Thus, whenever we are interested in only the resultant
external effects of a force, the force may be treated as a
sliding vector, and we need specify only the magnitude,
direction, and line of action of the force, and not its point of
application.
Because this course deals essentially with the mechanics of
rigid bodies, we will treat almost all forces as sliding vectors

6. Classification of Forces
• Force can be classified as either contact or
body force.
• Contact Force: : a contact force is a force that
acts at the point of contact between two
objects.
• Contact force is the force in which an object
comes in contact with another object.

7. Example of Contact force
• Force exerted on a body by a supporting
surface.

8. Body Force
• Body force is generated by virtue of position
of a body within force field.
• Example are gravitational, Electric and
Magnetic fields.

9. Concentrated Force
• When the dimension of the area are very small
compared with the other dimension of the
body, we may consider the force to be
concentrated at a point with negligible loss of
accuracy.

10. Distributed force
• Force can be distributed over an area as in case
of mechanical contact over a volume when a
body force such as weight is acting or over a
line as in case of the weight of the suspended
cable.

11. Concurrent Force
• Two or more forces are said to be concurrent
at a point if their line of action intersect at that
point.

12. TWO DIMENSIONAL FORCE
SYSTEM

13. Rectangular Component

20. Problem 2/1

21. Problem 2/2

22. Problem 2/3

23. Problem 2/4