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M1 Moments Help

Hello there,
okay, i need some help with moments...
I'm using the orange heinemann edexcel Mechanics 1 textbook, if anyone has it to hand, chapter 6A.
im a bit confused :
For Question 1, on page 134, i cant figure out how to work out the sense of the moment, i.e. whether its clockwise or anticlockwise.
any tips?
Thanks in advance :smile:
(edited 11 years ago)
Reply 1
I'd be happy to help, but I don't have the book!
Reply 2
Image166.jpg

For questions of type like e,f,h
Reply 3
Original post by Dhino
Hello there,
okay, i need some help with moments...
I'm using the orange heinemann edexcel Mechanics 1 textbook, if anyone has it to hand, chapter 6A.
im a bit confused :
For Question 1, on page 134, i cant figure out how to work out the sense of the moment, i.e. whether its clockwise or anticlockwise.
any tips?
Thanks in advance :smile:


can you post the question so someone can help you?

Edit: just seen your pictures! Are you taking moments about the point marked x? Start by drawing the perpendicular from x to the line of action of the force.
(edited 11 years ago)
Reply 4
Original post by davros
Are you taking moments about the point marked x? Start by drawing the perpendicular from x to the line of action of the force.


yeah, its the moment about X...
okay, so if i draw the perpendicular, what then?
cause i know i can work out the moment by using Fxdxsin(theta),
but then i cant imagine the sense of the moment (clockwise or anti clockwise)
Reply 5
Original post by Dhino
yeah, its the moment about X...
okay, so if i draw the perpendicular, what then?
cause i know i can work out the moment by using Fxdxsin(theta),
but then i cant imagine the sense of the moment (clockwise or anti clockwise)


OK, so if you take (e) for example, which is the simplest example, after you've drawn the perpendicular from x to the line of the force, imagine that perpendicular line swinging round in the direction of the force arrow. Is it going round in a clockwise direction or an anticlockwise direction?
Reply 6
Original post by davros
Is it going round in a clockwise direction or an anticlockwise direction?


that depends where its "attached"...?
as in it could open from where its meeting the line of the force and go clockwise
or open from where its at the x and go anti-clockwise :confused:



Edit: oooh i get it! its the moment about X, so i assume it opens where it meets the force line, using x as the rotation point, therefore its clockwise?
(edited 11 years ago)
Reply 7
Original post by Dhino
Image166.jpg

For questions of type like e,f,h


Imagine the dotted line is a lever, attached to a wall at the X, and you're pulling it in the direction of the arrow.
Reply 8
Original post by Dhino
that depends where its "attached"...?
as in it could open from where its meeting the line of the force and go clockwise
or open from where its at the x and go anti-clockwise :confused:



Edit: oooh i get it! its the moment about X, so i assume it opens where it meets the force line, using x as the rotation point, therefore its clockwise?


You got it :smile:
Reply 9
Thank you so much, its actually really simple :tongue:

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