Plastic pipe

Calculate the plastic pipe's weight with diameter d = 100 mm and length 330 cm if the wall thickness is 4 mm and the density of plastic is 1346 kg/m³.

Correct answer:

m =  5.36 kg

Step-by-step explanation:

$$\begin{gathered} d=100\text{mm}\to \text{cm}=100:10\text{cm}=10\text{cm} \\ l=330\text{cm} \\ s=4\text{mm}\to \text{cm}=4:10\text{cm}=0.4\text{cm} \\ \rho =1346{\text{kg/m}}^3\to {\text{g/cm}}^3=1346:1000{\text{g/cm}}^3=1.346{\text{g/cm}}^3 \\ {r}_1=d/2=10/2=5\text{cm} \\ {r}_2=r_1-s=5-0.4=\frac{23}{5}=4.6\text{cm} \\ {S}_1=\pi \cdot r_1^2=3.1416\cdot 5^2\doteq 78.5398{\text{cm}}^2 \\ {S}_2=\pi \cdot r_2^2=3.1416\cdot 4.6^2\doteq 66.4761{\text{cm}}^2 \\ {S}_3=S_1-S_2=78.5398-66.4761\doteq 12.0637{\text{cm}}^2 \\ V=l\cdot S_3=330\cdot 12.0637\doteq 3981.0262{\text{cm}}^3 \\ {m}_1=\rho \cdot V=1.346\cdot 3981.0262\doteq 5358.4613\text{g} \\ m=m_1\to \text{kg}=m_1:1000\text{kg}=5358.4613:1000\text{kg}=5.36\text{kg}=5.36\text{kg} \end{gathered}$$

Try another example