Concrete hatch

The concrete hatch for a round well has a diameter of 1300 mm and a thickness of 80 mm. Determine its weight in kg if the density of the concrete is 2545 kg/m³

Correct answer:

m =  270.2429 kg

Step-by-step explanation:

$$\begin{gathered} D=1300\text{mm}\to \text{m}=1300:1000\text{m}=1.3\text{m} \\ h=80\text{mm}\to \text{m}=80:1000\text{m}=0.08\text{m} \\ \rho =2545{\text{kg/m}}^3 \\ r=D/2=1.3/2=\frac{13}{20}=0.65\text{m} \\ S=\pi \cdot r^2=3.1416\cdot 0.65^2\doteq 1.3273{\text{m}}^2 \\ V=S\cdot h=1.3273\cdot 0.08\doteq 0.1062{\text{m}}^3 \\ m=\rho \cdot V=2545\cdot 0.1062=270.2429\text{kg} \end{gathered}$$

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