Finding moments about a point

  • Thread starter Bolter
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  • #1
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Homework Statement:
See below
Relevant Equations:
moment = force x perpendicular distance
Not sure if I answered this question right

Screenshot 2020-10-11 at 23.19.42.png

IMG_5352.JPG


I took my clockwise moments as +ve and counter-clockwise moments as -ve

Any help would be much appreciated! Thanks
 

Answers and Replies

  • #2
TSny
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Should ##F_x## be positive or negative?

Are you sure you took clockwise as positive for the moments? Does ##F_y## tend to rotate the object clockwise or counterclockwise?
 
  • #3
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Should ##F_x## be positive or negative?

Are you sure you took clockwise as positive for the moments? Does ##F_y## tend to rotate the object clockwise or counterclockwise?

Oh it looks like Fy is trying to rotate the bar counter-clockwise
whereas Fx is also rotating it counter-clockwise?

so lets say I took counter-clockwise to be a positive moment, then the moment about O is (Fx * 0.15) + (Fy * 1.5) = 3.74 kN?
 
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  • #4
Lnewqban
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It looks OK to me.
 
  • #5
TSny
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Oh it looks like Fy is trying to rotate the bar counter-clockwise
whereas Fx is also rotating it counter-clockwise?
Yes

so lets say I took counter-clockwise to be a positive moment, then the moment about O is (Fx * 0.15) + (Fy * 1.5) = 3.74 kN?
Looks good except for the units of the answer.
 

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