Weight and mass of an object are defined with Newton’s laws of motion. Which among the following is true ?

In Newtonian mechanics, mass is defined as a constant of proportionality. According to Newton's second law of motion, force is the product of mass and acceleration (F = ma), where mass (m) acts as the proportionality constant between the applied force and the resulting acceleration. Similarly, in the context of gravity, weight (w) is the gravitational force acting on an object, expressed as w = mg [1]. Here, mass serves as the constant of proportionality between weight and the acceleration due to gravity (g). While weight is a variable force that changes depending on the local gravitational field or planet, mass remains an intrinsic, constant property of the object regardless of its location [1][2]. Therefore, mass is the fundamental constant of proportionality in these physical relationships, whereas weight is a force and the universal gravitational constant (G) is a separate entity.

Sources

1. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 5: Exploring Forces > A step further > p. 75
2. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 5: Exploring Forces > Snapshots > p. 77