MOMENTS

MOMENTS

 @ moment of a force or moment :-

            the turning effect produce by a force about a point is caleed moment of a force or moment about that point
            the point about which moment is taken is called moment centre. the perpendicular distance from the moment centre to the line of action of a force is called moment arm. a force is acting on a rigid body 'F' for taking moment of this force about a point of draw a perpendicular from 'O' to the line of action of the force , now the moment of the force about 'O' is equal to Force ><moment arm that is = F >< d . thus, the moment of force at any point is calculated by the product force and the perpendicular distance from the point to the line of action of force. the moment of force whose line of action passes through the moment centre is zero
 Unit of moment of force = Nm (newton metre)

@ Types of moments :-

    there are two type of moments :-

i) Clock wise moment :-

           it is a tendency of force is to rotate the body clock wise, than the moment is called clock wise moment , these are taken as negative

ii) Anti clock wise moment :-

              if a tendency of a force to rotate the body anticlockwise then moment is anti-clock wise moment

@ varignon's theoram of moment :-

           it states that if a number of coplaner forces are acting simultaneouslly on a particle than if the alzebric sum of the moment of all the forces about any point in their plain is equal to the moment of their resultant about the same point

 @ Law of moments :-

        it states that if a number of coplaner forces are acting on a body and the body remains in equillibrium than the sum of clock wise moment is equal to the sum of anti clock wise moment

      @ Parellel forces :-

               the forces whose line of action are parellel to each other are known as parellel forces depending upon the direction parellel forces may be classified as-

a) Like parellel forces :-

            if the parellel forces acts in same direction they are called like parellel forces

b)  Unlike parellel forces ;-

           if the parellel forces act in opposite direction they are as unlike parellel forces

@ Couple ;-

           two equal , unlike parellel forces are said to constitude a couple
# Arm of couple :-
           the perpendicular distance between the line of action of two equal and unline parellel force is called arm of couple
# moment of couple ;-
          it is the product of one of the force forming the couple and arm of the couple. mathematically couple = F1d=F2d= F3d which results F1=F2= f
     it is also called torque , it is vector quanlity

@ effect of couple :-

             two corces the only effect that a couple produce n the body is that of rotation without moving the body is that of rotation without moving the body as whole resultant force is zero in the case of couple hence the the movement of the body is not possible

@ classification of couple ;-

           the couple may be clasifies into three categories

- Clock wise couple :-

               a couple ehose tendency is to rotate a body on which it act on a clock wise direction , a couple whose tendency is to rotate the body on which it act in on anticlock wie direction

@ charateristics of couple ;-

           * the alzebric sum of the forces constituting the couple is zero,
* The alzebric sum of movement of the forces constituting the couple about any point is the same  and equal to the moment of couple itself
* a couple can only be balanced by a couple not by a single force
* any number of coplaner couples whose magitude to a single couple whose magnitude will be equal to alzebric sum of the movement of all the couple