Mass, Weight and Density

Mass. Everyone knows what is mass. Everyone has a mass. However, do everyone know the difference between mass and weight?

No. People tend to say, "My weight is 50 kg." Same here. Before I learnt about this, I also make this mistake. In fact, I used to think that the were synonymous!

What about density? Not many know the word density, but about the idea behind density. For example, why do some things float on water while some sink in water? This is partially due to density.

Firstly, let me explain this three terms scientifically. Mass is the amount of matter inside any object. Mass is referring to the amount of matter packed in the object. The SI Unit of Mass is Kilograms (kg). Weight is the pull of gravity on the mass. Weight's SI Unit is Newton (N). So the difference? Mass is a scalar quantity, while Weight is a Vector quantity. (Scalar and Vector Quantity will be explained in the future blog post) Mass is a base quantity, while Weight is a derived quantity.

Equation of Weight

Density, also known as ρ, is also a derived quantity. It is defined as the mass of a substance per unit volume. An object that is denser if it has a greater amount of matter packed into the same volume compared to that of another object. Though the SI Unit is kg per meter cube, a common unit is gram per centimeter cube.