SIMPLIFIED: "7.3: Density"

Link: https://phys.libretexts.org/Bookshelves/Conceptual_Physics/Introduction_to_Physics_(Park)/03%3A_Unit_2-_Mechanics_II_-_Energy_and_Momentum_Oscillations_and_Waves_Rotation_and_Fluids/07%3A_Fluids/7.03%3A_Density 

Note: The image above was taken from the original article.

One of the most important and common topics when studying physics is fluids. In my personal opinion, the linked article above talks about one of the most important topics to fully understand before studying fluids: density! By the textbook definition, density is the amount of mass per unit volume. That basically means how much mass is in a specific amount of space (the specific amount of space is referred to as volume). 

Let’s look at some examples on how you can think about density. Here’s an easy example: if you have two identical boxes, where one is full of heavy dumbbells and the other is full of paper, the box with the heavy dumbbells has a higher density. Why? Because the box with the dumbbells has MORE mass in the same amount of volume/space. 

To calculate the density of an object, you can use this simple formula: density of an object = mass of the object divided by the volume of space that the object takes up. The simple formula that most people use is: p = m / v. The p looking simple represents density.

If you read the linked article above before just reading this simplified version, you might have noticed a chart that listed various densities for various liquids, solids, and gasses. You do not need to memorize any of those when doing problems with density, with the exception of water; you will likely need to memorize that the density of water is 1.000 kilogram per liter. 

You might be wondering why density is important at all. I said earlier that it is very important to understand density when studying fluids. This is because when an object is in a fluid, the object floats if the density of the object is less than the density of the fluid. On the other hand, the object will sink in the fluid if the object’s density is greater than the fluid. Finally, if the densities of the object and the fluid are the exact same, then the object will neither sink or float.