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# M1 Urgent help needed Watch

1. Moments is perpendicular distance but why is it in that q that the 3gcos30 isn't perpendicular?

Thanks
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2. (Original post by Trihawk7)
Moments is perpendicular distance but why is it in that q that the 3gcos30 isn't perpendicular?

Thanks
You want the length of either line in green - see attached. sin60 is the more obvious choice, but cos30 works out the same.

3. (Original post by ghostwalker)
You want the length of either line in green - see attached. sin60 is the more obvious choice, but cos30 works out the same.

But that isn't part of the 3g is it not?
4. (Original post by Trihawk7)
But that isn't part of the 3g is it not?
It's the line of action of the force that you're interested in, and this extends to infinity in both directions.
5. (Original post by ghostwalker)
It's the line of action of the force that you're interested in, and this extends to infinity in both directions.
I'm still confused because if you're using the line of action then the 3g isn't connected to it? sorry for being stupid
6. (Original post by Trihawk7)
I'm still confused because if you're using the line of action then the 3g isn't connected to it? sorry for being stupid
Not sure what you mean by the 3g isn't connected to the line of action.

The line of action is simply the line along which the force acts.
7. (Original post by ghostwalker)
Not sure what you mean by the 3g isn't connected to the line of action.

The line of action is simply the line along which the force acts.
How'd they get 3gcos30 then? sorry
8. (Original post by Trihawk7)
How'd they get 3gcos30 then? sorry
The perpendicular distance of the line of action is the green line in my previous diagram which is 1 x sin 60, hence a moment of 3gsin60 refering to the lower triangle.

They seem to have used the other angle in the triangle i.e. 30 degrees, in which case it's cos30 giving 3gcos30.

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