Задача id8861

The student solved the problem of a conical pendulum (Fig. 50). He believed that since ball A does not move in the direction O A, the resultant of all forces acting in this direction is equal to zero. Therefore T - mg cos α = 0 and T = mg cos α. Another student believed that since ball A does not move in the vertical direction, the sum of all forces acting in the vertical direction is zero. Therefore T cos α - mg = 0 T = mg / cos a Why did they come to different results?

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