A steel part weighing 75 kg has a volume of 15 dm3. determine if there is a cavity inside the part?

Given:

m = 75 kilograms is the mass of the steel part;

V = 15 dm3 (cubic decimeters) – the volume occupied by the steel part;

ro = 7800 kg / m3 (kilogram per cubic meter) – steel density (table value).

It is required to determine if there are cavities in the part.

Let’s translate the units of measurement of volume in the SI system:

V = 15 dm3 = 15 * 10-3 = 15/1000 = 0.015 m3.

Let’s find the actual density that the steel part has:

ro1 = m / V = 75 / 0.015 = 5000 kg / m3.

Since the actual density of the part is less than the density of steel (5000 <7800), it means that there are cavities in the part.

Answer: There are cavities in the part.