What is 'Density' and 'Pressure'?

Well, there is a relation between pressure and density. If I say clearly, pressure is an important thing when I am going to describe density. Now, I am going to teach you what's density and what's pressure. I will use the formulas of density and pressure, and I will take the help of Archimedes's law. Density vs Pressure graph.

Density:

At first, take a body near you. You can feel that this body has a mass. This also has a certain volume. Now can you say what the mass of every 1 m3 of this body is? That means, if the body is of 10 kg and its volume is 5 m³, then in every one cubic meter has 2 kg mass. And thus, the density of the body is two kg^-3. We can write the formula like-

If the density is D, the volume is V and mass is M, then-

D=M/V

Pressure:

You have that body used in understanding density in your hand. Now, place this body on the floor of your house. As the body has a mass, the floor is facing a force. The amount of the force is 98 N (F=mg). Now, if the body is giving force in a 10 m² area, then tell how much force is being applied every 1 m²? The amount is surely 9.8 N. Isn't it? And this is the pressure being given by the body on the floor. So we can say-

If the pressure is P, the force is F, and the area is A, then-

P=F/A

Definition of pressure.

The law of Archimedes.

The law of Archimedes:

If an object of Volume V is totally submerged in a fluid of density D, then-

The upward buoyant force: V×D×g

The downward force: m×g

If that body with 10 kg mass is in your hand, then it is giving a force 98 N. If you submerge it in water, then the water will also give a force. At a time when the water will give 98 N force, the body will be stopped in the water. Well, you will see the body is submerged partially or fully. It is only submerged fully when it is not possible to the fluid to give such force 98 N. The more is its density, the more it gives force. You can use any fluid instead of water.

We can write it shortly if the density of a fluid is 1000 kg/m^3, and the density of a body is 500 kg/m^3, and if you submerge it in the fluid, it will be submerged half. And if the density of the body is more than 1000 kg/m³ will be fully submerged and take place in the bottom of the pot(any jar used to keep the fluid). And this is the explanation of Archimedes's law.

The weight of a body decreases if it is submerged in water.

So, that's all I can say. Please pardon me if I have made any mistake in this article. And I had read this in my physics book. You can see it in the link I have given at last(the first one). Please read it and share your knowledge.

www.nctb.gov.bd

In the link over, go to the class 10 physics book. It is in Bengali, but you can also see this in English.

en.m.wikipedia.org

Go here and search 'Density' or 'Pressure' to see more.