i mean the horizontal metal rod id held by a cable , the cable is supported by the pin on the ground . My question is why the direction of tension of cable is in downward direction ?ogg said:I wonder if the problem statement "should" have said:"Let's say the metal rod is hanging by a cable and pinned at the bottom, the reaction of the cable is downwards..."?? If so, your diagram is all wrong. (by "pinned", I mean bolted into some fixture where it is free to rotate in one plane through 180° (forward parallel to flat horizontal ground -- to straight up (90°) -- to backward parallel to ground).) This is just a guess since imho the problem statement isn't clear enough to answer unambiguously.