The Principle of Moments/ Moment of a Force?

Question

a.)

is Clockwise(CW) direction = negative(-)???? and

Counterclockwise(CCW) direction = positive(+)?????

Answer 1

This principle is based on the right hand rule.  Make a fist, stick your thumb out like Fonzy on Happy Days.  Now curl your fist towards your wrist, as you will see, the thumb is facing you and if it is facing you, its positive (AAeyyy ) as Fonzy would say.  Now turn your thumb away from you and curl your fist, that is the negative direction.  When you curl in the positive direction, the curl is counterclockwise and your thumb is facing you in the positive, when you turn your thumb away from you, it is clockwise and negative.  The principle of moments, if referring it as a force or vector on a coordinate system, tells you in which direction a force a vector is pointing to.  In this case, your thumb tells you where the vector or moment direction if forces are acting on that system.  Lets say you have a cantilever beam in which its fixed end is at zero on the system and has a length "a" in the postive x-direction.  If a force "v" is applied at a distance "b" from 0 but less than "a", the moment is negative.  The vector causes the beam to want to rotate clockwise around point 0 on the coordinate system.    Make a fist, and try to make a curl direction in which the force vector "v" is causing the rotation at zero and it is in the same direction as the curling of your fist.  If you got that, stick your thumb out, that direction should be facing away from you and into the paper.  That direction is the moment vector in which the moment is pointing away from you.

Answer 2

now my dear, this depends on your option, that is, if u select the counter-..  to be positive then clockwise-...  will be negatve and vice versa, put this will influence the direction of the third access, we usually use the rule of s***w, becase we tighten the s***w by clockwise direction, when u rotatae the s***w clockwise the s***w goes down which is ur third acces directin and vice versa

Answer 3

You just have to be consistent.  I hate writing sum of the moment equations.  What I do is take the sum of all the moments going CW and set it equal to the sum of the moments going CCW.