The document discusses the fundamentals of engineering mechanics, detailing the behavior of bodies under the action of forces and classifying mechanics into three categories: rigid bodies, deformable bodies, and fluids. It categorizes forces into systems such as coplanar, non-coplanar, concurrent, and non-concurrent forces based on their lines of action and interactions. Additionally, it explains various types of coplanar and non-coplanar forces, highlighting their characteristics and relationships.

1. ENGINEERING MECHANICS - SYSTEM OF
FORCES & RESULTANT OF COPLANER
FORCES AND IN SPACE
By : Engr. Waqar Ahmed

2. INTRODUCTION
 Mechanics is the science that describe and
predicts the conditions of inertia and motion
of bodies due to the action of forces.
Mechanics and its classification
 Depending upon the nature of the body, the
transmission of forces may cause the body to
deform internally or may not produce any
deformation but the body may tend to move
due to it. Accordingly, the subject of
mechanics can be broadly classified into
1. Mechanics of rigid bodies
2. Mechanics of deformable bodies
3. Mechanics of fluids

3. SYSTEM OF FORCES
Collinear
Coplanar Non-Coplanar
Concurrent Non-Concurrent Concurrent
Non-
concurrent
Like Unlike
Paralle
l
Non-
parallel
Like Unlike
Paralle
l
Non
parallel
Like Unlike
System of Forces: A body with two or more forces acting simultaneously on it constitute a system of
forces.

4. Like Collinear
 Coplanar Forces: All the forces act in one plane. Here, the line of action of Forces F1, F2
and F3 lies in single plane ABCD. This system is also called as “Forces in plane”.
 Non-coplanar Forces: The forces do not act in one plane. Here, the line of action of
Force F2 lies in ABCD plane, but line of action of the force F1 lies in ADEF plane. This
system is also called as “Forces in space”.
 Collinear Forces: The forces which acts on a common line of action are called collinear
forces. If they act in same direction, they are called like collinear and of they act in
opposite direction, they are called “Unlike collinear”.
Unlike Collinear
Coplanar Forces Non-Coplanar Forces

5. Like & Unlike Parallel
 Concurrent Forces: Forces intersects at a common point.
 Parallel Forces: Line of action of forces are parallel to each other. Parallel forces acting
in same direction are called like parallel forces and the parallel forces acting in opposite
direction are called unlike parallel forces.
 Like Collinear coplanar Forces: Forces acting in same direction, lies on a common line of
action and acts in a single plane.
 Unlike Collinear coplanar Forces: Forces acting in opposite direction, lies on a common
line of action and acts in a single plane.
Concurrent Forces
Like & Unlike Collinear coplanar
Forces

6.  Coplanar concurrent Forces: Forces intersects at a common point and lies in a single plane.
 Coplanar non-concurrent Forces: Forces which do not intersect at a common point, but acts in
one plane. They may be wither parallel or non-parallel.
 Non-coplanar concurrent Forces: Forces intersects at one point, but their line of action do not lie
on the same plane.
 Non-coplanar non-concurrent Forces: Forces do not intersects at one point and also their lines of
action do not lie on the same plane.
Coplanar
concurrent Forces
Coplanar non-
concurrent Forces
Non-Coplanar non-concurrent
Forces
Non-Coplanar concurrent
Forces

37. Thank you
Questions ?