Engineering Statics

B-12


The tailgate of a sport utility vehicle is supported by the pneumatic strut BC. If the strut exerts a 120 lb force, determine the moment of the force about the hinge at point A.

The hypotenuse of each triangle is found.
The components of the force are found using the knowledge that the 
components of the force are proportional to the components of the 
geometry.
Using arithmetic the force is found.
To find the moment, any distance from the pivot point to any point 
on the line of action of the force may be used.  Hence the distance 
AB or AC may be used.
The distance from A to B is given in vector form.
The cross-product of the distance, AB, and the force is taken using 
the cross-product determinant.

The distance from A to C is found." >
The cross-product of the distance, AC, and the force is taken using 
the cross-product determinant.