We explain what specific weight is and what the formulas are to calculate it. Also, some examples and their relationship with density.

## What is specific weight?

The specific weight is the **existing relationship between the ** **weight** ** and the ** **volume** ** that occupies a ** **substance** **in space**. It is the weight of a certain amount of substance divided by the volume it occupies. In the International System it is expressed in units of *Newtons* about *cubic meter (N/m ^{3}).*

The calculation of specific gravity requires other properties of the substance, such as density and mass. Mathematically, the specific gravity **It is represented by the symbol gamma (γ) and is expressed as**:

*γ (specific weight) = w (ordinary weight)* / *V (volume of substance)*or what is the same: *γ = w/V = mg/V,* where *m* is the mass of the substance and *g* is the acceleration of gravity (commonly considered as *9.8m/s ^{2}*). As the density

*(ρ)*of a substance is defined as

*m/V*the specific weight can be written as

*γ=ρ.g.*

## Examples of specific weight

Some examples of specific weight of different materials are:

- Gypsum: 1250 N/m
^{3} - Cal: 1000 N/m
^{3} - Dry sand: 1600 N/m
^{3} - Wet sand: 1800 N/m
^{3} - Loose cement: 1400 N/m
^{3} - Concrete tiles: 2200 N/m
^{3} - Poplar Wood: 500 N/m
^{3} - Ash Wood: 650 N/m
^{3} - American pine wood: 800 N/m
^{3} - Steel: 7850 N/m
^{3} - Aluminum: 2700 N/m
^{3} - Bronze: 8600 N/m
^{3} - Lead: 11400 N/m
^{3} - Zinc: 7200 N/m
^{3} - Iron casting: 7250 N/m
^{3} - Water: 1000 N/m
^{3} - Asphalt: 1300 N/m
^{3} - Stacked paper: 1100 N/m
^{3} - Slate: 2800 N/m
^{3} - Tar: 1200 N/m
^{3} - Granite: 2800 N/m
^{3}

## Specific weight and density

The relationship between the specific weight *(mg/V)* and the density *(m/V)* is analogous to that which exists between the weight* (mg)* and the dough* (m)* of a substance. It is evident that the more mass a certain amount of a substance has, the greater its weight. In the same way, the denser that amount of substance is, the more mass that enters a certain volume, the greater its specific weight will be, since the greater “mass due to gravity” will enter that volume.