Volume of a rectangular bar = length x breadth x height
V = L x B x H
Let us consider a rectangular bar of length 1m, breadth 20mm = 0.020m and height 10mm = 0.010m
Hence, Volume = L x B x H = 1 x 0.020 x 0.010 = 0.0002m3
So, mass of rectangular bar = density x volume = 7900 x 0.0002 = 1.58 kg
Similarly, we can calculate the mass of a rectangular bar of different dimensions.