Weight

Weight is not the same as mass. Whereas mass is the property of matter and a measurement of inertia, weight is actually the gravitational force of a planet (such as earth) acting on the object. Therefore, weight varies depending on the gravitational force. On the surface of earth, the weight of an object is the product of the mass and the acceleration due to gravity of earth. The SI unit for weight is Newton (N). The formula is shown below:

where g is the acceleration due to gravity, and has a value of 9.8 m/s². This formula can be derived by using the Newton's law of universal gravitation. The m₁ and r can be replaced with mass of the earth and the distance from the center to the surface of the earth respectively. And together with G, the value of G · M_E/r² is 9.8 m/s², the acceleration due to gravity.