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# M1 one moments how do i decide if the moment direction clockwise or anti clockwise? watch

1. I don't know how to do this please explain this to me.

Thank you.
2. Erm... that's extremely vague. What direction is the force going in?
3. (Original post by Chwirkytheappleboy)
Erm... that's extremely vague. What direction is the force going in?
the force is going to the left of p, there is a per distance which connects p with F .
4. (Original post by Core)
the force is going to the left of p, there is a per distance which connects p with F .
ok, so what is the position of p with respect to F? Might be easier if you just draw a diagram, it should be fairly obvious from there
5. (Original post by Chwirkytheappleboy)
ok, so what is the position of p with respect to F? Might be easier if you just draw a diagram, it should be fairly obvious from there
can i draw one on here?
6. (Original post by Core)
can i draw one on here?
You should be able to draw it in Paint or something and add it to a post as an attachment
7. o yes thanks il do that, one moment please
8. the way I did it, cos I suck at mechanics :

get a pen, hold it in the middle and push up or down depending on the direction of the force shown and see which way the pen moves.

You look like a freak doing it but oh well.
9. ok
Attached Images

10. (Original post by Anita B. Studin)
the way I did it, cos I suck at mechanics :

get a pen, hold it in the middle and push up or down depending on the direction of the force shown and see which way the pen moves.

You look like a freak doing it but oh well.
Push up or down i just tried it but nothing happened.
11. (Original post by Core)
Push up or down i just tried it but nothing happened.
So hold the pen from where you want to calculate the moment, like point P or whatever. If they show you a diagram with the arrow (force) pointing down, then push the pen down roughly around the same place as the diagram and it will move.
12. Also this one i got the question right but the direction wrong...
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13. Right... diagram isn't the easiest to interpret but I'm assuming that the angle between the two lines is supposed to be a right angle because it sort of looks like you've drawn a slanted right angle box. I'm also assuming that the direction of the force is upwards to the left (you should really draw an arrow to be clear). The force is going upwards and to the left. That's the direction of the moment
14. Do you mean the light from the pin will turn?
15. (Original post by Chwirkytheappleboy)
Right... diagram isn't the easiest to interpret but I'm assuming that the angle between the two lines is supposed to be a right angle because it sort of looks like you've drawn a slanted right angle box. I'm also assuming that the direction of the force is upwards to the left (you should really draw an arrow to be clear). The force is going upwards and to the left. That's the direction of the moment
But they say its clockwise. They don't use left or right.
16. Clockwise then. Same thing.
17. (Original post by Chwirkytheappleboy)
Clockwise then
Well i already knew which direction this one was going in as they told me, but how do i know how to tell for myself this was an* example in* the book.
18. (Original post by Core)
Well i already knew which direction this one was going in as they told me, but how do i know how to tell for myself this was an* example in* the book.
Are you sure you're not overthinking this? It's just a case of simply looking at which direction the force is going in, as shown here
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19. (Original post by Chwirkytheappleboy)
Are you sure you're not overthinking this? It's just a case of simply looking at which direction the force is going in, as shown here
So thats what they mean. Thank you, i have one more i have an issue with. Can you help me with this also please, the example states that

"Considering the moments about point A:
"
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20. (Original post by Core)
&quot;Considering the moments about point A:
&quot;
Pivots tend to be fixed points (unless you have a more dynamic system than you'd typically see at A level) so you assume that the rod is stationary and therefore the clockwise moments equal the anticlockwise moments.

Considering the moments about A, there is a downwards force of 20N which is 1.5m away, and an upwards force of RcN which is 2m away (expressed as 1.5+0.5 because they're the measurements shown on the diagram). The downwards force creates a clockwise moment which must be equal to the anticlockwise moment produced by the upwards force. Hence the equality

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