[Daily Question] Theoretical Basis 2020.01.17
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Multiple choice questions: The figure shows a square OABC with side length a. known: Force F1=F2=F3=F4=F, couple moment M1=M2=Fa. The principal loss and principal moment of this force system after being simplified toward point O should be ( ) Answer: D Translate F2 and F3 to point O respectively, add a couple respectively, and the couple moment is Fa. In this way, a plane intersection force system is obtained, whose principal loss is zero. ； At the same time, a plane couple system is obtained, whose principal moment is 2 Fa and the direction is clockwise. The resultant moment of M1 and M2 in the original picture is zero. hint: Those who can explain the problem-solving process will be given extra rewards, and the answers will be visible in the reply!
D Translate F2 and F3 to point O respectively, add a couple respectively, and the couple moment is Fa. In this way, a plane intersection force system is obtained, whose principal loss is zero. ； At the same time, a plane couple system is obtained, whose principal moment is 2 Fa and the direction is clockwise. The resultant moment of M1 and M2 in the original picture is zero.