Mass and Weight

We all use these two words often, mass and weight. But what is the difference between these two? How are they different? And what do they signify? We shall try and find answers to these questions in this article.

Now, coming to mass, it is actually quite difficult to define mass. Mass a fundamental property of matter, there is no matter without mass, everyone and everything around you has mass. It is almost impossible for me to put mass into words. We can just understand that mass is associated with matter. The SI unit (internationally accepted scientific unit) of mass is Kilogram (kg). Actually, we cannot even actually measure mass directly, to measure mass we need to measure weight first and then when we divide weight by the gravitational field we get the mass [I will make a separate article on gravitational field and potential]. Now coming to weight, weight is nothing but a kind of force. It is the reaction force of the normal force exerted by the ground on us, this normal force depends on the gravitational force. Also the gravitational force depends on mass, the normal force depends on the gravitational force and our weight is the reaction of the normal force. Thus, mass is related to weight but not directly. The magnitude of weight, which is a force, is equal to that of the normal force and opposite in direction.

Now our weight depends on many factors, it is not always the same. The primary factor affecting our weight is the gravitational field we are in. We would weigh one sixth on the moon of what we weigh on earth. But our mass always remains same. This is because the gravitational field on moon is one sixth of that on earth. The other factor which affects weight is our location on earth, we would weigh different on the poles than we weigh on the equator. As I had mentioned in the previous article gravitational force depends inversely on the radius, and the radius of the earth varies a bit from latitude to latitude because the earth is not a perfect sphere. Thus, due to change in radius, gravitational force changes and so does our weight. The other factor contributing to the change in our weight is the rotation and it is somewhat related to latitudes.

It’s amazing how our weight depends on so many different factors. This is just a speck of wonderfulness compared to the rest of physics. Trust me Physics is epic and very interesting. I hope you learned something new today. Thanks for reading!!!