Equilibrium of a particle

In physics, equilibrium of a particle refers to a state in which a particle is at rest or moving with a constant velocity and experiences zero net force. In other words, when a particle is in equilibrium, it is not accelerating.

There are two main types of equilibrium for a particle:

1. Static Equilibrium: In static equilibrium, the particle is at rest. This means that both its translational motion (linear motion) and rotational motion (if applicable) are not changing. Static equilibrium is commonly observed in scenarios where objects are at rest, such as a book lying on a table or a bridge structure.

2. Dynamic Equilibrium: In dynamic equilibrium, the particle is moving with a constant velocity, but it is not accelerating. This means that the vector sum of all external forces acting on the particle is still zero, but the particle is not necessarily at rest. Dynamic equilibrium can occur when an object is moving at a constant speed in a straight line or when an object is moving in a circle at a constant speed. An example of dynamic equilibrium is a car traveling on a straight road at a constant velocity.

In both static and dynamic equilibrium, the key concept is that the net force (and net torque, if applicable) acting on the particle is zero. This is based on Newton's first law of motion, which states that an object at rest tends to stay at rest, and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an external force.