Cylinder-shaped 31951

How many kg of paint do you need to buy to paint a 1.5m high cylinder-shaped rainwater cover with a 0.7m radius? We paint the barrel from the outside and inside, and 100 grams of paint is needed to paint 1 square meter.

Correct answer:

m =  1.9352 kg

Step-by-step explanation:

$$\begin{gathered} h=1.5\text{m} \\ r=0.7\text{m} \\ {S}_1=\pi \cdot r^2=3.1416\cdot 0.7^2\doteq 1.5394{\text{m}}^2 \\ S=2\cdot S_1+2\pi \cdot r\cdot h=2\cdot 1.5394+2\cdot 3.1416\cdot 0.7\cdot 1.5\doteq 9.6761{\text{m}}^2 \\ f=100\text{g}\to \text{kg}=100:1000\text{kg}=0.1\text{kg} \\ m=2\cdot S\cdot f=2\cdot 9.6761\cdot 0.1=1.9352\text{kg} \end{gathered}$$

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