How can density be negative? | Density,Unit of Density

No, the Density of a substance can never be negative. Because it depends on the mass and volume of a substance. Mass can never be negative, and the negative Volume of a substance doesn’t make any sense.

Introduction: –

Whenever we are looking around us we are seeing many things. All these things are made of atoms. These atoms are arranged differently in different substances.

Let’s discuss this arrangement with some examples.

We take three different substances of the same sizes in three different states Solid, Liquid, and Gas. In the case of solids atoms are arranged very close and have more number of atoms in comparison to liquid and gas.

If we arrange the solids, liquids, and gases according to number of atoms in these substances


Now the question arise in our brain HOW WE CAN TELL ABOUT THIS?

For this we should have to know about density

How can a density be negative  Density,Unit of Density.

What is DENSITY?

It is defined as mass per unit volume of a substance.

In general,it tell us that How much heavy that object with the same Volume.

If the substance have more mass concentrated on the unit volume. We can say the object will have more density.

If we arrange the state of matter according to increasing order of density


Solid Liquid Gas Density


Formula for density

Formula used for measuring Density

Density =Mass/Volume.

Can density be Negative | Formula of Density

Symbol used for density

If we use rho ( ρ ) for Density, m for mass and V for Volume of substance.

Formula will be as given above.

Unit of density | SI unit of Density

In SI Unit, if measure mass in terms of Kilogram (kg) and Volume in terms of cubic metre ( m³).Then,

We can measure density in terms of SI UNIT OF DENSITY kg/m³.

Other unit of Density

Density can also be measured in terms of gram per cubic centimetre (g/cm³), gram per millilitre (g/ml).

Dimensional formula of density

If we talk about dimensional formula of density.

Mass have dimensional formula [M] and Volume have dimensional formula [L³].

So Dimensional formula for Density will be [ML-3]

Can density of a substance change?

Density of a substance can not change with the change in the amount of substance present.This is because the density is Intensive property.

On the other hand Mass of substance changes as mass is an extensive property.

Mass per unit volume means the density should not changes.As with the change in the amount of substance changes side by side the volume of a substance should also changes. But the ratio of these two term mass upon volumne remains constant with the change in the amount of substance.

Factors Affecting the Density:-

Density of a substance depends on the following four factors:

Density is directly proportional to Mass of the substance

More will the mass of the substance in the given volume more will be the density of substance.

Density is inversly proportional to volume of the substance

Lesser will the volume of the substance in the given Mass, more will be the density of substance.

Density is inversly proportional to temprature of the substance

As the temprature of the substance changes the molecule of the substance gain some energy due to which volume of the substance increase and density of the substance decreases.

Density depends on the physical state of the substance.

Density of the substance depends on the mass and volume both. If we take the same amount (mass) of substances all are present in the different states.Then the substance which is in the solid state have the small volume due to which it have the more density.On the other hand,in the gaseous state the Moleucles are loosly packed and have more volume. Due which gaseous state have less density.
The densities of the different states varies as

Solid > Liquid > Gases

Does temperature affect density?

Yes temprature also affect the density of substance. BECAUSE if object is object is heated up then the particles of substance will expand and loosely packed. So the substance will have less density. If we cool the substance at lower temperature substance will have very closely packed.

How does density of a substance change with temperature?

Whenever we heat the substance then the molecules of the substance gain some kinetic energy due to which they starts moving randomly in all directions.
When they start moving with kinetic energy, molecules or atoms of the substance occupying more volume. Due which the volume of the substance increases which leads to the decrease in the density of a substances.

How Is Density Calculated?

To understand how to calculate Density of a substance. LET’S DISCUSS IT with an example.

Problem: Calculate the density of a substance which have 50g of mass is concentrated on 200cm³.

Solution: Mass of substance= 50g

Volume of Substance=200 cm³

We know that

Density formula=Mass/Volume

Density of substance=50g/200cm³.


Application of Density in Real Life

1.If we will mix oil with water in a beaker. We will observe that the oil will start floating on the surface of water.

 Reason: This is because the density of water is more in comparison to oil. So all will start floating on the surface.Oil on Surface of Water

Image Source

2.If we will place a steel ship on the surface of water, ship will start floating on the water. Even a steel density is more than the water.

Reason: But Most of the space in the ship is filled with the air Which will make it less dense in comparison to the water. So, ship will start floating on the surface.

Density can never be negative.

3.If we will compare the weight of the wood. With the same amount of water. The wood weight will be very less in comparison to water.

Reason: The wood is less dense than the water. So, wood will start floating in the water.

Is density directly proportional to pressure?

Yes, the density is directly proportional to pressure.
According to the Boyle’s Law the Pressure is inversly proportional to the Volume and Density is also inversly proportional to the volume.So, the density is directly proportional to the Pressure.

Is density extensive property?

Yes density is extensive proporty.
Now the question arise what is extensive and intensive property
Extensive Property the property which is depends upon the size of the system particles or amount of material.
if Amount of the substance change that physical quantity also changes.
So Density is an Extensive property.

Intensive Property the property which does not depends upon the size of the system particles or amount of material.
if Amount of the substance change that physical quantity does not changes.
So Mass is an Intensive property.

Is density and volume the same

No both are two different terms. They are related to each other. As the Density is mass per unit volume.
Density can be find out from the volume by dividing the mass with the volume.

Does density change with size?

Density is the intensive property. It does not depend upon the shape size of the object. If the particle size will be changes, it does not affect the density of that substance. If we will divide a large size object into the millions of the small sized objects, the density of that substance, it will remain same.

Can density be less than 1

Yes, the density of the substance it can be Less than one. If the density of a substance be less than 1 it means the Substance is less denser in comparison to the other substance. If the density is greater than one, it means that the particles of the exceptions that are very closely packed and have more density.

Can density be changed by force

Yes, the density can be changed by applying the force on the substance. If you. If you will apply that the more force per unit area. It means we are applying the more pressure due to increase in the pressure. The particles of the substance, they come very close to each other, which leads to decrease in the volume. So with a decrease in the volume, then the density of the substance, it will be increases.

Can density be a decimal

Just a density of the substance can be possible in decimal.
As the density of the substance is mass upon volume. Mass and the volume both can be in the decimal as 2.5 kg and 3.5 m3. So by dividing these two terms with the Formula Mass upon volume, the Result come out in the decimal.


The concept of Density is more important because it will tell us. The substance, which substance will float, which substance will be sink when we place it in a liquid.

Generally Substances float on the surface of other liquid whose density is less than that liquid they are placed in.


Q1.Why does density depend on mass?

Ans: It is defined as mass per unit volume of a substance. Density is directly proportional to mass and inversely proportional to volume of the substance. More will be the mass of the object in constant volume, More will be the density of substance.

Q2.What is Density?

Ans:It is defined as mass per unit volume of a substance

Q3.Who discovered the principle of Density?

Ans: The Great Greek Scientist Archimedes had discovered this principle of Density.

Q4:How would you find the density of a human body?

Ans: The density of a human body can be find by the following formula:

Density = Mass / Volume

We can measure the mass of the person using the weighing machine. For finding the volume of the person, if we will immerse the person, in the tub filled with water. The amount water raised in the tub will be the volume of the person. Both the values of mass and volume. We can measure the density of the person.

Q4: How will we know if a substance is less dense than water?

If we take two substances of equal volume. The substance whose weight is LESS will be having LESS Density.

Q5: What are the SI Unit of Density ? What is the Dimensional formula of Density?

The SI Unit of Density is kg/m3. It can also be measured in the g/cm3 or g/l.The Dimensional formula for the density is [ML-2]

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