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+### Statement
+
+$2.3.15.$ [Insert the problem statement]
+
+### Solution
+
+### Statement
+
+$2.3.15.$ What minimum work must be done to raise a long uniform pole of length $l$ and mass $m$ lying on the ground to a vertical position?
+
+### Solution
+
+For a uniform pole, its center of mass is located exactly in the middle. When lying on the ground, the height of its center of mass is $0$. When placed vertically, the center of mass is raised to a height of $h = \frac{l}{2}$.
+
+The minimum work done is equal to the increase in the potential energy of the center of mass:
+$$A = mgh = mg\frac{l}{2}$$
+
+#### Answer
+$$A = mg\frac{l}{2}$$
+
+#### Answer
+
+[Insert a concise answer or boxed result]