Physics in Simple Terms: 8 Facts About Liquid Density & How to Measure It

Growing up, nothing was more heartening than pillow fighting with your siblings. You could laugh and have fun while running up and down your decker bed, everyone armed with a pillow. It’s one of those memories that still leave a ton of nostalgia among us, grownups.

One of the reasons why these fights were thrilling is because each pillow had lots of soft, fluffy stuffing-like feathers. See, it is the density of the content that makes the pillows soft enough to cause no bodily harm – the matter stuffed inside has a low density. Unlike those other heavier materials, you swing it, and it hits your sibling, no damage is caused.

You can imagine the kind of injuries had you switched your soft, feather-light pillows for something more substantial!

So, what is Liquid Density and how is it measured?

Density is a word that’s often thrown about, but perhaps hard to unambiguously confusing to define. It can be described as the amount of space an object, body or substance takes up in relation to how much matter it has. Simply put, it is the amount of mass per every unit of volume a body has.

You can find the density of an object when you have its volume and mass, essentially using the formula: Density = mass/volume

From this formula, a body that’s heavy and compact, say a rock, brick or a piece of metal, will understandably have high density. On the contrary, light objects that are equally voluminous will have a low density.

Liquids have their respective densities, and these variations are down to their masses and volumes. To understand what liquid density is, however, you have to look at it in several perspectives. Primarily, you must determine the following:

  •         The mass of the liquid.
  •         The volume of the liquid.
  •         What the fluid is.

8 Facts about Liquid Density and How to Measure It

Fact #1: It’s far much easier to determine the density of a liquid substance

That’s right; you can find liquid density in a much easier way compared to discovering that of a solid or gaseous material. You simultaneously measure the volume and mass of a liquid because it is the same thing.

The most important thing, however, is to pay keen attention to the density gauges used, whether it is graduated cylinders or beakers. Check it and ensure you calibrate it well so that the volumes are accurate. If it isn’t correct, use the manual adjustments or its automatic ‘tare’ function so that the scale is at the ‘zero’ scale.

Fact #2: It’s 100% possible to change the density of a substance, EXCEPT water!

It may sound outrageous, but this is absolutely true. You can change the density of an object when you focus on reforming its mass and volume. And the way to do that is to decrease its temperature so that the molecules inside of it stop moving. For them to stop moving, they’ll need less space, which will then force the density to increase.

The opposite is true if you want its density to decrease. This rule, however, doesn’t include any liquid matter. Water will expand when it freezes, and the resulting blocks of ice will be less dense than liquid water. This can happen when water is stored in stainless steel as well.

Fact #3: Did you know that before transporting any liquid matter, its liquid density has to be determined?

Well, this is a well-known tradition amongst those drivers of tankers and those who transport liquid products on a regular basis. To them, the essence of knowing the density of the product helps them understand the best way of carrying it. This fact is also applicable when pumping liquids.

Fact #4: Density comes into play when pricing petroleum

Being a favorite source of power for automobiles, petroleum is priced differently in various parts of the world. What many don’t know, however, is that the product’s density also contributes the price discrepancies.

First, the liquid density of it gives an estimate of how much kerosene or other gasoline contained in it. And when that has been deduced, the relevant authorities use that to determine the price it should retail at.

Also, when it comes to measuring crude oil, the standard unit of measurement is metric tons. And so, when the liquid density is determined, calculating the number of barrels in every metric ton becomes possible when API gravity is known.

Fact #5: When it comes to the liquid density of soft drinks, you can use it to predict the number of sugars it has

This particular fact is based on the other well-known fact which goes like ‘As ingredients change, so does the density of the liquid.’ This fact is probably more telling where a predictive correlation is applicable.

When it comes to soft drinks, those with more sugar content will automatically have a higher liquid density than its sugarless alternative. The sugars increase its density. This property is typically used in the production of drinks and beverages.

Fact #6: Use the density of a liquid to calculate its mass

Density and mass are related, and that means you can find a liquid density of a substance using its mass. This fact is very critical in engineering, essentially using the same formula of using the density formula:

m = ρ × V

This fact comes in handy in various situation, especially when you can’t find out how much space an object has or the maximum mass it can carry.

Fact #7: Liquid density is used in shipyards when manufacturing ships

A little piece of stone will quickly drop to the seabed, but a sack filled with feathers will float in the same water, and that’s because of their relative densities. Stone has a higher frequency than water, and that’s why it sinks no matter how small or big it is. This fact is highly critical in determining what material to use when manufacturing water vessels.

Fact #8: Ever heard of the ‘Eureka moment’ and how it came about?

This term dates back to centuries ago when the famous Greek philosopher Archimedes had been tasked with the role of determining if King Hiero’s goldsmith was being stolen. When Archimedes discovered that a product displaces water that’s equal to its volume, he was extremely excited.

He would use the volume to find the density and thus compare that density with the resulting density of the King’s gold. This discovery was so exciting to him that he had to dash to the streets, shouting “Eureka! Eureka” meaning “I have found it!”


Ajay Deep

Ajay Deep is a young enthusiast who Loves Chandigarh and is always eager to make this beautiful city even more beautiful. A Mechanical Engineer By Chance and Working in an IT MNC by Choice. A Writer, Photographer and a Budding Entrepreneur. A Designer, Developer and Digital Marketing Expert. In brief : A Jack of All Trades and Master of Few :) You may reach Ajay Deep at
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