The discussion revolves around finding the axial force at point X in a structural analysis problem. Participants are analyzing a given structure and attempting to determine the nature of the axial force, whether it is tension or compression, based on their calculations and reasoning.
Participants express differing views on the correct approach to isolating sections of the structure and the interpretation of axial force direction. There is no consensus on the correct nature of the axial force at point X, as participants are still debating whether it is tension or compression.
Participants have not fully resolved the implications of their calculations, particularly regarding the sign convention for axial forces and the effects of vertical forces at point B on the axial force at point X.
PhanthomJay said:You went through more work than necessary, you could have isolated a section of the right hand part with a cut at x to find the axial force. Your answer looks numerically correct, but is the axial force compression or tension in the member?
Isolate from point x to D.DanRow93 said:Which right hand part do you mean I could have isolated, from point X to C? It would be compression I think, so should be -5.08?
PhanthomJay said:Isolate from point x to D.
Compression is correct, but why do you say that?
PhanthomJay said:Isolate from point x to D.
Compression is correct, but why do you say that?
when you isolated the section AB, the vertical force at B acts downward on AB. (Don't rotate the members as you have done, this confuses the issue). Anyway, if the vertical force at B acts downward on AB, then what does Newton's third law tell you about the direction of the vertical force at B on BC?DanRow93 said:I actually don't know, I've confused myself. At point B the axial force along BC is downwards, so axial force in X is opposite which means it should be tension doesn't it
the problem statement tells you that a positive value for the axial force in BC indicates tension, implying that compression is entered as a negative value.I put the answer 5.08 into the online test that I had to do and I got it wrong...