Ch 4. Moments/Equivalent Systems st Multimedia Engineering Statics Moment2-D Scalar Moment3-D Scalar Moment3-D Vector Couples and Equiv. System Distributed Loads, Intro
 Chapter 1. Basics 2. Vectors 3. Forces 4. Moments 5. Rigid Bodies 6. Structures 7. Centroids/Inertia 8. Internal Loads 9. Friction 10. Work & Energy Appendix Basic Math Units Sections Search eBooks Dynamics Statics Mechanics Fluids Thermodynamics Math Author(s): Kurt Gramoll ©Kurt Gramoll

 STATICS - EXAMPLE Example Fixed Bracket with Force A single force of 14 kN acts on a bracket that is fixed to a wall. What is the total moment in vector format at point A due to the force? Solution To find moment about a point, the position vector from the point of interest to any point on the force line of action is crossed with the force vector. In equation form this is      MA = r × F Position Vector r from Point A to the Force Line of Action For this problem, the position vector is drawn from point A to point E giving      rAE = 6i - k Another position could be used, such from A to D. The force vector can be determined by multiply its magnitude with its unit directional vector. The location of point D and E is (8,8,2) and (6,0,5) respectively. The force vector is      F = F uDE             = -3.191i - 12.764j + 4.786k Substituting into the cross product gives,      This determinate can be evaluated as,     MA = -12.76i - 25.52j - 76.58k