STATICS

STATICS

Statics is the branch of mechanics which deals with the study of bodies at rest under a number of forces, the equilibrium, conditions of equilibrium, types of equilibrium and torque etc.

EQUILIBRIUM

A body is said to be in equilibrium if it is at rest or moving with uniform 

velocity.

In other words if the linear and angular acceleration of a body are zero, the body is said to be in equilibrium.

Or we can say that when two or more forces act on a body such that their resultant or combining effect on the body is Zero and the body retains its state of rest or of uniform motion then the body is said to be in equilibrium.

EXAMPLE

A book lying on the table, suspended bodies, all stationary bodies etc.

CONDITIONS OF EQUILIBRIUM

There are two conditions of equilibrium are as follows

• First condition of equilibrium
• Second condition of equilibrium

STATES OF EQUILIBRIUM

There are three states of equilibrium:

• Stable equilibrium
• Unstable equilibrium
• Neutral equilibrium

STABLE EQUILIBRIUM

When the center of gravity of a body lies below point of suspension or support, the body is said to be in STABLE EQUILIBRIUM.

EXAMPLE

A book lying on a table is in stable equilibrium.

UNSTABLE EQUILIBRIUM

When the center of gravity of a body lies above the point of suspension or support, the body is said to be in unstable equilibrium

EXAMPLE

Pencil standing on its point or a stick in vertically standing position.

NEUTRAL EQUILIBRIUM

When the center of gravity of a body lies at the point of suspension or support, the body is said to be in neutral equilibrium.

EXAMPLE:

Rolling ball.

TORQUE

The torque or moment of force can be define as

“The tendency of a force to produce rotation in a body about an axis is called torque or moment of force."

Positive torque:

If a body rotates about its axis in anti-clockwise direction, then the torque is taken positive.

Negative torque:

If the body rotates in the clockwise direction, then the torque is taken as negative.

CENTER OF GRAVITY

The center of a body is that point in the body through which the resultant forces due to the earth’s attraction possess and through which the whole weight of the body always acts.

OR

Center of gravity of a body is a point where total weight of the body is concentrated.