In that case, if the body is known to such indicators as the volume (V) and density (p) for calculating the body mass will need to use the formula: m = p*V.
For clarity, you can give an example. You want to find the mass of a concrete slab whose volume is 15 m3.
Solution: for finding the mass of the concrete slab is required to know only its density. In order to learn this information, you need to use a table of densities of various substances.
According to this table the density of concrete is 2300 kg/m3. Then to find the mass of the concrete slab, you will need to perform simple algebraic action: m = 15*2300 = 34500 kg, or 34.5 tons. Answer: the mass of the concrete slab is 34.5 tons
Mass measurement in the traditional way using one of the oldest instruments of mankind - with the help of weights. This is due to the comparison of body weight with the reference weight of cargo weights.