Direction of Moment: 1200N at A- Clockwise or Counterclockwise?

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The discussion centers on the direction of the moment produced by a 1200 N force at point A, questioning why it is considered counterclockwise in the textbook. It clarifies that while the force creates a clockwise moment, the reaction moment (MA) at the beam's connection to the wall must be counterclockwise to maintain equilibrium. Participants note that both moments can be treated as equal and opposite, leading to confusion about their directions. Ultimately, the reaction moment is correctly identified as counterclockwise, aligning with the textbook's explanation. Understanding these moments is crucial for solving equilibrium problems in mechanics.
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Homework Statement


Why shouldn't the direction of moment for 1200n at A =clockwise? Why the book gave counterclockwise?

Homework Equations

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It depends if you are talking about the moment of the force (1200 N), which is turning clockwise or if you are looking at the reaction moment in the connection of the beam to the wall (MA), which has to turn counterclockwise to establish the equilibrium. Two moments of the same size in two different directions.

EDIT: Sorry, I didn't look at the drawing well: The moment MA of course must be the sum of the moments produced by the force (1200 N) and the weight of the beam (both with clockwise direction).
 
Last edited:
stockzahn said:
EDIT: Sorry, I didn't look at the drawing well: The moment MA of course must be the sum of the moments produced by the force (1200 N) and the weight of the beam (both with clockwise direction).
Well, no, as you wrote in the first paragraph MA would be equal and opposite to the sum of those two moments, hence anticlockwise.
Anyway, it really doesn't matter which way it is presumed to be. MA could be taken to be clockwise, and the equations written accordingly. It would then turn out to have a negative value.
 
the correct
haruspex said:
Well, no, as you wrote in the first paragraph MA would be equal and opposite to the sum of those two moments, hence anticlockwise.
Anyway, it really doesn't matter which way it is presumed to be. MA could be taken to be clockwise, and the equations written accordingly. It would then turn out to have a negative value.
the correct moment would be in clockwise direction , right ? the anticlockwise in merely the reaction of the moment produced which is in opposite direction , am i right ?
 
haruspex said:
[] ... MA would be equal and opposite to the sum of those two moments, hence anticlockwise.

That was what I meant to say in my EDIT. Sorry for the ambigous expression.
 
goldfish9776 said:
the correct moment would be in clockwise direction , right ? the anticlockwise in merely the reaction of the moment produced which is in opposite direction , am i right ?
In the textbook extract you posted, MA is the reaction moment. Read it carefully. There is no error there.
 

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