There is a granite monument with a height of 38m, a length of 15m and a thickness of 3M. In order to know its gravity, a small sample of granite is taken and its mass is 39.2g measured by a balance. It is tied with a thin line and immersed in a measuring cylinder filled with 70ml water. The water surface rises to the position where the scale is 84ml. The gravity of the monument is calculated

There is a granite monument with a height of 38m, a length of 15m and a thickness of 3M. In order to know its gravity, a small sample of granite is taken and its mass is 39.2g measured by a balance. It is tied with a thin line and immersed in a measuring cylinder filled with 70ml water. The water surface rises to the position where the scale is 84ml. The gravity of the monument is calculated

(1) The volume of granite sample: V sample = 84ml-70ml = 14ml = 14cm3, m sample = 39.2g, the density of granite: ρ = m sample, V sample = 39.2g, 14cm3 = 2.8g/cm3 = 2.8 × 103kg / m3; (2) the volume of stele: V ′ = 38m × 15m × 3M = 1710m3, the mass of this stele: m ′ = ρ V ′ = 2.8 × 103kg / m3 × 1710m3 = 4.788 × 106kg. (3) the gravity of this stele: g = m ′ = 4.788 × 106kg × 9.8n/kg A: the gravity of this monument is 4.7 × 107n