In one sentence, describe what the following article is about:

To calculate mass from volume, you must know the density of the object. Different materials have different densities. Consider a sphere made of styrofoam, for example, and compare its weight to a sphere the same size made of iron. Iron has a much greater density and will therefore have a greater mass.  You can find densities of many solid materials by looking up density tables online, in textbooks or in other industry catalogs. For example, here are the recorded densities of some solid materials: Aluminum = 2700 kg/m3  Butter = 870 kg/m3  Lead = 11,350 kg/m3  Pressed wood = 190 kg/m3 The units you used in calculating volume must match the volume units in the density measurement. If they do not, then you must convert them.  All of the examples in the previous section resulted in volumes measured in cubic centimeters. However, the cited density table provides densities based on cubic meters. Because there are 100 centimeters in a meter, there are 106 cubic centimeters in a cubic meter. Divide the given densities by 106 to represent the density in units of kg/cm3. (You can do this most easily by just moving the decimal point 6 spaces to the left.) For the four sample materials, the converted densities are as follows:  Aluminum = 2700 kg/m3 = 0.0027 kg/cm3  Butter = 870 kg/m3 = 0.00087 kg/cm3  Lead = 11,350 kg/m3 = 0.01135 kg/cm3  Pressed wood = 190 kg/m3 = 0.00019 kg/cm3 Recall that the formula for density is Density=MassVolume{\displaystyle {\text{Density}}={\frac {\text{Mass}}{\text{Volume}}}}. Rearranging this to find the mass, the equation becomes Density∗Volume=Mass{\displaystyle {\text{Density}}*{\text{Volume}}={\text{Mass}}}. Using the four sample materials, aluminum, butter, lead and pressed wood, find the mass of a sphere that has a volume of 500 cm3.  Aluminum:500 cm3∗0.0027kgcm3=1.35 kg{\displaystyle {\text{Aluminum}}:500{\text{ cm}}^{3}*0.0027{\frac {\text{kg}}{{\text{cm}}^{3}}}=1.35{\text{ kg}}} Butter:500 cm3∗0.00087kgcm3=0.435 kg{\displaystyle {\text{Butter}}:500{\text{ cm}}^{3}*0.00087{\frac {\text{kg}}{{\text{cm}}^{3}}}=0.435{\text{ kg}}} Lead:500 cm3∗0.01135kgcm3=5.675 kg{\displaystyle {\text{Lead}}:500{\text{ cm}}^{3}*0.01135{\frac {\text{kg}}{{\text{cm}}^{3}}}=5.675{\text{ kg}}} Pressed wood:500 cm3∗0.00019kgcm3=0.095 kg{\displaystyle {\text{Pressed wood}}:500{\text{ cm}}^{3}*0.00019{\frac {\text{kg}}{{\text{cm}}^{3}}}=0.095{\text{ kg}}}
Find the density. Convert the units as needed. Multiply volume by density to find mass.