Law

According to Newton's third law of motion, every action has an equal and opposite reaction. These action-reaction forces act on different objects. The real-world example is a person walking, when the person takes a step forward, their foot pushes backward on the ground, the ground also exerts an equal and opposite force forward on the person's foot and the person is propelled forward due to the reaction force from the ground. Another real-world example is the rocket launch which expels hot gases downward (action), the gases exert an equal and opposite upward force (reaction) on the rocket and cause upward acceleration. It is an important point to remember that the action and reaction forces act on different bodies and hence although they are equal and opposite, they do not cancel each other out.

Newton's second law states that an object's rate of change of momentum is in the direction of the force, and it is directly proportional to the applied force. Mathematically, it is represented as F=ma. F is the net force acting on a body which is the vector sum of all individual forces acting on it. Here, m represents the mass of the object and a is the acceleration of the object, which is a vector quantity and it is the rate of change of its velocity. Newton's second law establishes a direct proportional relationship between an object's acceleration and force and an inverse proportional relationship between the object's mass and acceleration.

Newton's First Law of Motion is also known as the Law of Inertia. It states that unless acted upon by an unbalanced force, the object in motion stays in motion in the same direction and with the same speed and the object at rest stays at rest. The fundamental concept of inertia is introduced by the first law of Newton which refers to the resistance an object shows to changes in its state of motion. It is an inherent tendency of an object. Inertia is directly proportional to an object's mass which implies that a massive object has greater inertia and will require more force for velocity changes.Newton's First Law of Motion implies that to cause acceleration i.e. velocity changes, a net force is needed and in the absence of the net force, the objects maintain their current state of motion. This law challenges the earlier Aristotelian view which stated that to keep an object moving, a continuous force is required.