Question

The cross-sectional area of a proposed roadway, for the site, cutting taken at 20 m intervals are shown in the following table Area (m2) 48.0 54.2 61.2 72.8 77.8 68.9 65.2 60.1 55.3 Chainage (m) 20 40 60 80 100 120 140 160 (a) Draw and label the cross-section of the roadway (b)Calculate the volume of material to be excavated (c) If granite with density 2.75 g/cm3 underlie the site, determine the position centre of mass of the material to be excavated (d) Determine the position of centroid of the granite underlying the site Comment: for (c) and (d) Use chainage 0 as the origin.

Answer 1

69 48 2 o 4o Go 8o 100 120 11Lo ets use pos 2rol nule to find Yolunta, ase excavated mateni al、 e) 20 148 455 rot 54 2x20 叶65.2 지 20 t 60,1x140 t 55.3x16。 Σ (ordinates o&ahla) (563S) 了| rm