Introduction- Coplanar forces means the forces in a plane. The word collinear stands for the forces which are having common lines of action whereas the word concurrent stands for the forces which intersects at a common point. When several forces act on a body, then they are called a force system or a system of forces. In a system in which all the forces lie in the same plane, it is known as coplanar force system. Hence this chapter of engineering mechanics deals with a system of forces which are acting in the same plane and the forces are either having a common line of action or intersecting at a common point.
Classification of a force system
A force system may be coplanar or non coplanar. If in a system all the forces lie in the same plane then the force system is known as coplanar. But if in a system all the forces lie in different planes, then the force system is known as con-coplanar. Hence a force system is classified as shown in fig. 1
 |
| Fig. 1 Classification of a force system |
In this chapter, we shall discuss only coplanar force system, in which the forces may be-
[i] Collinear
[ii] Concurrent
[iii] Parallel
[iv] Non-concurrent, non-parallel{or general system of forces}
[i] Coplanar collinear- In the fig. a , three forces F1, F2, F3 are acting in a plane. These three forces are in the same line. i.e., these three forces are having a common line of action. This system of forces is known as coplanar collinear force system. Hence in coplanar collinear system of forces, all the forces act in the same plane and have a common line of action.
 |
| a- Coplanar collinear forces |
[ii] Coplanar Concurrent- In the fig. b, three forces F1, F2, F3 are shown, acting in a plane and these forces intersect or meet at a common point O. This system of forces is known as coplanar concurrent force system. Hence in coplanar and concurrent system of forces, all the forces act in the same plane and they intersect at a common point.
 |
| b- Coplanar Concurrent forces |
[iii] Coplanar Parallel- Fig. c, shows three forces F1, F2 and F3 acting in a plane and these forces are parallel. This system of forces is known as Coplanar Parallel force system. Hence in Coplanar Parallel system of forces, all the forces act in the same plane and are parallel.
 |
| c- Coplanar Parallel forces |
[iv] Coplanar Non-concurrent, non-parallel{or general system of forces}- Fig. d, shows four forces F1, F2,F3 and F4 acting in a plane. The lines of action of these forces line in the same plane but they are neither parallel nor meet or intersect at a common point. This system of forces is known as Coplanar Non-concurrent, non-parallel force system. Hence in Coplanar Non-concurrent, non-parallel system of forces, all the forces act in the same plane but the forces are neither parallel nor meet at a common point. This force system is also known as general system of forces.
 |
| d- Non-concurrent, non-parallel |
Telegram channel- Join Now
0 Comments
Please let me know, if you want to know something else or in case of any doubt.