How to determine which point to take the moment about?

[CCenturion]

Problem -

1. The T-shaped bracket shown is supported by a small wheel at E and pegs at C and D. Neglecting the effect of friction, determine the reactions at C, D, and E when the angle is 30 degrees.
   
   I have taken the moment about E, and gotten a result for all the reactions. However, in the solutions it says that i should be taking the moment about D.
   I don't understand what the difference is between picking one point or the other.
   Please refer to the two attached pictures. Thank you

 

[nasu]

See template for homework section.
You did not show neither the problem nor your solution.

 

[PhanthomJay]

Problem -

1. The T-shaped bracket shown is supported by a small wheel at E and pegs at C and D. Neglecting the effect of friction, determine the reactions at C, D, and E when the angle is 30 degrees.
   
   I have taken the moment about E, and gotten a result for all the reactions. However, in the solutions it says that i should be taking the moment about D.
   I don't understand what the difference is between picking one point or the other.
   Please refer to the two attached pictures. Thank you

For a system in equilibrium, you can sum moments about any point = 0, but you can simplify the number of steps and reduce chances for errors when summing moments about a selectively chosen point. You might want to first solve for Ex and Ey, then sum moments about D (or C) to see how this works.

 

[CCenturion]

Got it Phantom, Thanks a lot !

 

[HalfLostAndSearching]

To determine the appropriate point to take the moment about, it is important to consider the overall equilibrium of the system. In this case, the T-shaped bracket is in a state of static equilibrium, meaning that all forces acting on it are balanced and there is no net movement.

When taking the moment about a point, we are essentially summing up the torques (rotational forces) acting on the system. The chosen point should be one that simplifies the calculations and allows for the unknown reactions to be solved for easily.

In this problem, it seems that both points E and D could be viable options for taking the moment. However, taking the moment about D may be more advantageous because it eliminates the unknown reaction at E, making it easier to solve for the reactions at C and D. Additionally, taking the moment about D may also provide a more accurate representation of the forces acting on the peg at D, as it is directly supporting the bracket.

Overall, the choice of which point to take the moment about may vary depending on the specific problem and what makes the calculations simpler. It is important to carefully consider the equilibrium of the system and choose the most appropriate point for taking the moment.