Chapter II
Force Systems 2D
Definition
• A force can be defined as the action of one body on
another that changes/tends to changes the state of
the body acted on.
• A force can be applied on a body as;
Contact force:-Applied by direct mechanical contact of
the acting body on the acted one (Created by push and
pull).
Remote action (Body force):-Applied by remote action as
in gravitational, electrical, Magnetic, etc forces.
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Definition Cont…
• Categories of force depending on their
arrangement in space.
Coplanar Forces:- are forces which act on the
same plane.
Non coplanar forces:- are forces which act on
different planes
» Non coplanar parallel forces
» Non-coplanar concurrent forces
» General Non coplanar force
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Definition Cont…
• Categories depending on their
arrangement in plane
Coplanar collinear forces
Coplanar parallel forces
Coplanar concurrent forces
General coplanar forces
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Definition Cont…
• Coplanar collinear forces:- are coplanar forces
acting on the same line-collinear.
• Coplanar parallel forces:- Are forces which are
on the same plane and parallel
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Definition Cont…
• Coplanar concurrent forces:- Are forces on the
same plane whose lines of action intersect at a
point.
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Definition Cont…
• General coplanar forces
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Ɵ
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Example 2/3
Given vector A with the following properties:
Magnitude= 150, Ɵz =450, Ɵy= 600, and it is known
that Ax is directed in the positive x direction. Express
the vector in Cartesian form.
Example 2/4
Determine a unit vector normal to the plane of the
triangle formed by three points: (0,0,2), (2,0,0), and
(0,2,0)as its vertices.
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Example 2/
2/35
A vector F has a magnitude of 2 and is directed from
point A to point B as shown in the figure below.
Calculate the projection of this vector onto line CD
and determine also the angle between F and CD.
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Definition
• Moment (torque )
•Tendency of a force to
rotate a body about a
given axis.
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
bbbbbbbbbbbbb
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Couple
• moment produced by 2 equal and
opposite forces is known as a
couple.
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Couple Cont…
• Moment of couple about any point
of reference 0.
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Couple Cont…
• Moment of couple about any point of
reference 0.
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Couple Cont…
• Moment of couple about any point of
reference 0.
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Couple Cont…
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering
Couple Cont…
• Resolution of a force into a force and a
couple equal external effect.
AAIT
Engineering Mechanics Statics
Tewodros N.
Department of
Civil Engineering