【Daily Question】Theoretical Foundation 2020.01.05
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Multiple-choice question: The force polygon of the planar concurrent force system (F1, F2, F3, F4, F5) is shown in the figure; the resultant force of this force system is equal to ( ). A.F3 B.-F3 C.F2 D.F5 Answer: B According to the polygon rule of forces, the force vector triangle formed by connecting F1, F2, and F3 end to end is self-closing, with zero-length sides; therefore, the resultant force of F1, F2, and F3 is zero. The remaining two forces, F4 and F5, are connected end to end, and their resultant force should point from the starting point of F4 to the ending point of F5, that is, in the direction of -F3. Hint: An additional reward will be given to those who can explain the problem-solving process; the answers can be seen here!
B According to the polygon rule of forces, the force vector triangle formed by connecting F1, F2, and F3 end to end is self-closing, with zero-length sides; therefore, the resultant force of F1, F2, and F3 is zero. The remaining two forces, F4 and F5, are connected end to end; their resultant force should point from the starting point of F4 to the ending point of F5, that is, in the direction of -F3