Third law of motion is also called

Question

Accepted Answer

The correct option is (3):
The Third Law of Motion, one of Sir Isaac Newton's foundational principles of classical mechanics, is known as the Law of action and reaction. This fundamental concept states that for every force, or "action," exerted by one object on a second object, the second object exerts a force, or "reaction," on the first object that is equal in magnitude and opposite in direction. These forces always exist as pairs and act on different interacting objects. Understanding this law is crucial for explaining how movement is generated, such as how the backward force of a swimmer's hands pushing the water results in an equal and opposite forward reaction force that propels the swimmer through the pool.

The incorrect option is (1):
The Law of inertia is the traditional and descriptive name for Newton's First Law of Motion. This law deals with the tendency of an object to resist changes in its state of motion. Specifically, it posits that an object at rest will remain at rest, and an object in motion will remain in motion with constant velocity, unless acted upon by a net external force. While inertia is closely related to mass, it is not the alternative name for the third law, but rather the cornerstone of the first law.

The incorrect option is (2):
The Law of acceleration is the universally accepted alternative name for Newton's Second Law of Motion. This law provides the mathematical definition of force, stating that the force acting on an object is equal to the product of its mass and its acceleration ($\text{F} = \text{ma}$). The second law determines how an object's motion changes when a non-zero net force is applied, establishing a cause-and-effect relationship between force and acceleration.

The incorrect option is (4):
Law of speed is not a recognized term for any of Sir Isaac Newton's three laws of motion. Speed is a scalar quantity describing the rate of motion and is a component of velocity, which is fundamental to the first and second laws. The three laws govern the relationship between force, mass, and motion (inertia and acceleration). There is no distinct law in classical physics that is named after speed, making this option conceptually incorrect.