Question

Define and explain Equilibrium in Physics with examples.

Answer 1

Equilibrium, in physics, the condition of a system when neither its state of motion nor its internal energy state tends to change with time. A simple mechanical body is said to be in equilibrium if it experiences neither linear acceleration nor angular acceleration; unless it is disturbed by an outside force, it will continue in that condition indefinitely. For a single particle, equilibrium arises if the vector sum of all forces acting upon the particle is zero. A rigid body (by definition distinguished from a particle in having the property of extension) is considered to be in equilibrium if, in addition to the states listed for the particle above, the vector sum of all torques acting on the body equals zero so that its state of rotational motion remains constant
eg when you are calm and steady

Answer 2

When a number of forces acting on a body produce no change in the state of rest of the body or state of motion of the body. Then the certain body is said to be in equilibrium.

The body becomes equilibrium under two conditions
1. The resultant of all the forces acting on the body is zero.
2. The algebraic sum of moments of all forces about the fixed point is zero.

Examples:
1. A book lying on a table:
When a book lies on the table, the force exerted by the book on the table is balanced by the force exerted by the table on the book. So, the book remains in the state of rest.

2. When the electrons move around the nucleus of an atom, the attractive force of the protons is balanced by the repulsive force of electrons between. So, the electrons remain in the state of motion.


Hope my answer helps you.