The discussion revolves around calculating moments using the Method of Joints in static equilibrium problems. Participants clarify that when taking moments about point B, only forces acting on the boom (members AB and BC) are considered, excluding forces at point C (Cx and Cy). The author’s approach simplifies the calculation by setting Ay to zero, which is a valid method for this specific problem. The conversation emphasizes the importance of free body diagrams (FBDs) and the need to focus on relevant forces for accurate moment calculations.
PREREQUISITESStudents in engineering mechanics, structural engineers, and anyone involved in analyzing static structures and forces.
If I consider the rod CB only, then my moment about B = Cy(8) =0... Then Cy =0... But in the author's working, the author found that Ay = 0billy_joule said:It's right.
Your subsequent working must have had an error as your conclusion was incorrect.
Why not try again, be more careful with your algebra and see how far you get.I'm not sure what you mean by that.
You forgot to include Cx.chetzread said:If I consider the rod CB only, then my moment about B = Cy(8) =0... Then Cy =0... But in the author's working, the author found that Ay = 0
My answer is different with the authors ans
OK, I gt the answer... So for this type of problem which involve multiple force member, we should consider forces equilibrium in 1 force member only if we can't solve the forces using equilibrium at all 3 members ?billy_joule said:You forgot to include Cx.
In this case we only consider moment about B in a rod only? If we consider moment about B in 2 rods, we can't solve the question?chetzread said:OK, I gt the answer... So for this type of problem which involve multiple force member, we should consider forces equilibrium in 1 force member only if we can't solve the forces using equilibrium at all 3 members ?
I'm not sure if there's a hard and fast rule.chetzread said:OK, I gt the answer... So for this type of problem which involve multiple force member, we should consider forces equilibrium in 1 force member only if we can't solve the forces using equilibrium at all 3 members ?
I am not concerned about the speed of solving the question...billy_joule said:I'm not sure if there's a hard and fast rule.
Seeing the quickest and easiest approach will come with practice.
This particular problem could be solved much faster with the method of joints.
Can you show how do you solve the question by method of joints?billy_joule said:I'm not sure if there's a hard and fast rule.
Seeing the quickest and easiest approach will come with practice.
This particular problem could be solved much faster with the method of joints.
Best to wait until after you've learned the method in class.chetzread said:Can you show how do you solve the question by method of joints?