 output.to from Sideway
Mechanics: Statics

System of Forces Transformation

Draft for Information Only

# Content

`System of Forces Transformation Force Couple Force Vector`

# System of Forces Transformation

Sometimes a system of forces acting on a rigid body is needed to be transformed into an equivalent system at the point of interest.

## Force Couple

A couple of force F is applied at points A, B on a rigid body. The equivalent system is a free couple vector M acting on any location of the rigid body. Consider the moment MBA at point B,  the tendency of rotation above B is caused by the applied force F at A. The applied force -F at B can be considered as the reaction supporting force. Both the magnitude and direction of the moment vector MBA  is same as the couple vector M. ## Force Vector

Suppose a force vector acting at point A on the rigid body is to be considered at point B. When only a single force F is applied at point A on the rigid body, the moment of the force at point A about point B is also equal to  MBA . To simulate the force couple condition, two forces, F and  -F with magnitude equal to the applied force F are attached at point B. After this transformation, a force couple of moment MBA is formed with an additional force -F acting at point B. Force F acting at point A is now moved to point B. The formed force couple of moment MBA can be replaced by a couple vector M. The couple vector M is a free vector and it can be located at point B for convenience. Therefore the equivalent system of a force vector F acting at point A on a rigid body can be transformed to an arbitrary point B by moving the force vector to pont B and adding a couple vector M with moment equals to the moment MBA of the force vector F about point B. At which, the force vector F tend to provide the same linear motion and the couple vector M tend to provide the same rotational motion as the force vector F at point A. The equivalent system of combining a force vector and a couple vector is named as force-couple system. And the couple vector is ID: 110700010 Last Updated: 12/7/2011 Revision: 1 Ref: References

1. I.C. Jong; B.G. rogers, 1991
2. F.P. Beer; E.R. Johnston,Jr.; E.R. Eisenberg, 2004  Home 5

Management

HBR 3

Information

Recreation

Culture

Chinese 1097

English 337

Computer

Hardware 149

Software

Application 187

Numeric 19

Programming

Web 757

CSS 1

HTML

Knowledge Base

OS 389

MS Windows

Knowledge

Mathematics

Algebra 20

Geometry 18

Calculus 67

Engineering

Mechanical

Rigid Bodies

Statics 92

Dynamics 37

Control

Physics

Electric 10