Specific gravity in its literal terms is the ratio of the density of a substance to the density of a given substance material. It is precisely known as relative density. Also, the relative density of an object can be measured as the density of that object to the density of water.

Concept of Density – a density of an object is a measure of how heavy or compact that substance is in a given volume or reference substance. Generally one measures density in mass per unit volume which is written using measures like grams per millilitre, grams per cubic meter or kilograms per litre 

Specific gravity formula –a specific gravity determines about how dense or light an object can be thus it can be generated by a comparative analysis of mass, weight, or density of the amount of the object or any fluid with that same amount of water at four degree Celsius.

Specific Gravity = mass of a unit of the substance /mass of a unit volume of water

Examples –

When the density of gold is 19,300 kilograms per meter cubed, so the specific gravity of gold is 19.3 where the density of water is considered to be 1000 kilograms

The density of vinegar is 1400 kilograms, keeping the water to 1000 kilograms dense the density of vinegar shall be 1.4. 

Method for determining specific gravity is-

• Hydrometer 
• Specific – gravity bottle 

Application of specific gravity – 

• Gem purity – The value of the gem can be determined by comparing its specific gravity with the patron number where a patron number is the measure of a gem as per its high purity 
• Soil’s compressive strength – specific gravity and compressibility are closely connected can be valued from each other’s density. This is basically for the knowledge of an engineer for the density of the soil for choosing a construction method
• Oil industry – Specific gravity measures the relationship between volume and weight where crude oil and other refined products are usually measured by gallons and US barrels and also by weight in tons.

Use of specific gravity – to exhibit a mixer, knowing the specific gravity of the liquid which is mixed is important because it will directly influence the torque and horsepower which is essentially required to mix that particular liquid. While the application along with higher specific gravity more of the torque shall be required to produce the required mixer. Also if there was no consideration of specific gravity a blended mixer could not be optimized and thus results could have been unpredictable leading to remote damage.

Hydrometer – A specific device technically used to measure the specific gravity of solid or liquid, it is helpful in a way that it floats in liquid leading to the application of the floatation principle, where the weight of the floating body is equal to the weight of the liquid displaced. Initially, there are two types of hydrometer which consist of a hollow cylinder which floats in the liquid with a stem in upper parts, they are –

• Variable immersion 
• Constant immersion 

Float Vssink 

When one object floats and others sink this is because the density of an object is related to another important factor called specific gravity. Since the specific gravity is the ratio between the density of an object and a reference substance, the specific gravity value obtained shall signify us whether the substance will sink or float. Very often it is observed that for these type of situations the reference substance is considered to be water which always has a density of 1 gram per millilitre or 1 gram per cubic centimetre.