Equilibrium:
The state of body under the action of many forces acting together but there is no change in transitional and rotational motions of the body is called equilibrium.
Or
A body is said to be an equilibrium if known it force acts upon it.
Or
If a body is in the state of rest or moving with uniform motion is called equilibrium.
Types of equilibrium:
There are two main types of equilibrium.
Static equilibrium: when a body is at rest under the action of several forces acting together the body is said to be in static equilibrium.
OrWhen all the forces acts on in object are balanced then the object is said to be at static equilibrium.
Example of static equilibrium : A book is lying on a table the weight of the book acting downward is balanced by the upward normal force of the table .
Hence it is an example of static equilibrium.
Dynamic equilibrium: The type of equilibrium in which there is no change in the motion of a body under the action of many forces is called dynamic equilibrium.
Example: The motion of an object under direction of gravity in which it is moving with constant motion or acceleration(g).
The dynamic equilibrium is further divided into two sub types
1) Dynamic transitional equilibrium:
The type of dynamic equilibrium in which there is no change in the transitional motion of a body under the action of several forces is called dynamic transitional equilibrium.
Example: The motion of an object under direction of gravity in which it is moving with constant acceleration (g).
2)Dynamic rotational equilibrium:
The type of dynamic equilibrium in which there is no change in the rotational motion of a body under the action of many forces is called dynamic rotational equilibrium.
Example: The example of rotational dynamic equilibrium is the compact disc (CD) rotating in CD player in show constant rotational motion therefore there is no change in its rotational motion and hence it is an example of dynamic rotational equilibrium.
Conditions of equilibrium: There are two conditions of equilibrium.
First condition of equilibrium: when sum of all the forces acting on the body is zero then the first condition of equilibrium is satisfied.
Mathematically:
Fnet = F1+F2+F3......+Fn.
Second condition of equilibrium: when the sum Of all the Torques acting on the body is 0 then the second condition of equilibrium is satisfied.
Ï„ total = Ï„1+Ï„2+Ï„3.......Ï„n.
The second condition of equilibrium is also defined as. The sum of all clockwise Torques equal to the sum of all anti clockwise Torques.
