| ### Statement: | | ### Statement: |
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| $4.1.2.$ A rectangular prism is in a liquid; its dimensions are shown in the figure. Find the sum of the forces acting on the front and bottom faces of the prism if the pressure of the liquid is $2 \cdot 10^5$ Pa. What is the sum of the forces acting on the prism? | | $4.1.2.$ A rectangular prism is in a liquid; its dimensions are shown in the figure. Find the sum of the forces acting on the front and bottom faces of the prism if the pressure of the liquid is $2 \cdot 10^5$ Pa. What is the sum of the forces acting on the prism? |
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| ### Solution: | | ### Solution: |
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| The pressure on the faces of the prism: | | The pressure on the faces of the prism: |
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| P = \rho \cdot g \cdot h = 2 \cdot 10^5 ~ \text{Pa}. | | P = \rho \cdot g \cdot h = 2 \cdot 10^5 ~ \text{Pa}. |
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| Since the dimensions of the prism are small compared with the depth, we consider the pressure constant over its entire height. | | Since the dimensions of the prism are small compared with the depth, we consider the pressure constant over its entire height. |
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| The pressure forces on the front and bottom faces are equal and are determined by the hydrostatic pressure $P$ and the area of a face of the prism: | | The pressure forces on the front and bottom faces are equal and are determined by the hydrostatic pressure $P$ and the area of a face of the prism: |
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| F_1 = F_2 = P \cdot a^2. | | F_1 = F_2 = P \cdot a^2. |
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| Since the two faces are perpendicular, we find the resultant force using the Pythagorean theorem: | | Since the two faces are perpendicular, we find the resultant force using the Pythagorean theorem: |
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| |F_{\text{R}}| = \sqrt{F_1^2 + F_2^2} = 2000 \sqrt{2} ~ \text{N} | | |F_{\text{R}}| = \sqrt{F_1^2 + F_2^2} = 2000 \sqrt{2} ~ \text{N} |
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| According to Pascal's law, the pressure is balanced, and the resultant force: | | According to Pascal's law, the pressure is balanced, and the resultant force: |
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