Force

Force :-

• Force is the interaction between two bodies.
• Force is the action of one body on another body that tries to change the motion of the other body.
• Force is a Vector quantity. It is characterised by :-
  1. Magnitude
  2. Point of Application
  3. Line of Action(Direction)

Principle of Transmissibility of Force:-

The point of application of forces can be moved anywhere along the line of action of forces without changing the external effect of the forces on the rigid body.

Moment of Force:

• Moment of force is the measure of tendency of force to rotate a rigid body about a fixed axis.
• Moment of force is the turning effect of force.
• Moment of force is a Vector Physical Quantity.
• It has magnitude and direction both.

Magnitude of Moment of Force :-

Product of magnitude of force and perpendicular distance from the line of action of force to the point or axis about which we have to calculate the moment of force.

Moment of Force = Force x Perpendicular Distance

M = F x D

• Point at which the moment of force is acting is known as Moment Centre.
• Perpendicular distance is known as Moment Arm.
• Where the sense of rotation is clockwise then the direction of moment of force is inward to the plane along z-axis(perpendicular to the plane(x-axis and y-axis)).
• When sense of rotation is counter clockwise then the direction of moment of force is outward of the plane along z-axis
• Pure rotation due to moment of force is produced in only hinged/pinned joint.

Couple :-

A couple is defined as two parallel forces that have same magnitude, but opposite direction and are separated by a perpendicular distance. is known as Couple.

Moment of Couple:

• Two equal and unlike parallel force acting on a body and separated by a distance apart then the moment of couple is the product of the magnitude of forces and the perpendicular distance between the action lines of the forces.
• Moment of couple gives pure rotation(always).
• Magnitude of moment of couple either direction wise or sense of rotation about any point is same.

Moment of Couple = Force x Distance between force of couple

M = F x d

Force Couple System :-

• Force couple system is obtained by resolving a given force into a force and couple.
• When a given force is transferred to another point away from the line of action, it will convert into force couple system.
• Net effect on coplanar non-concurrent force system is Force Couple System