Newton's Second Law Explained

The statement, "The rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of the force," directly defines Newton's Second Law of Motion.

This law mathematically relates force ($\vec{F}$), momentum ($\vec{p}$), and time ($t$) as:

$ \vec{F} = \frac{d\vec{p}}{dt} $

Where:

• $\vec{F}$ is the net applied unbalanced force.
• $\frac{d\vec{p}}{dt}$ represents the rate of change of momentum with respect to time.

This relationship highlights that a greater force produces a greater change in momentum, and the change happens in the direction of the force.

Why Other Laws Are Incorrect

• Newton's First Law of Motion (Law of Inertia) describes the state of rest or uniform motion in the absence of net force. It doesn't directly address the rate of change of momentum due to a force.
• Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. This deals with forces between interacting objects, not the rate of change of momentum of a single object.
• Newton's Fourth Law of Motion does not exist as a standard law in classical mechanics.

Therefore, the described rule is unequivocally Newton's Second Law of Motion.