Search
 
 

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

     
   
 
Practice Homework and Test problems now available in the 'Eng Statics' mobile app
Includes over 500 problems with complete detailed solutions.
Available now at the Google Play Store and Apple App Store.