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Topic - Moments Question Physics/Maths/engineering?

lowersharpnose - on 28 Nov 2012
I can't get my forces to balance in a trivial moments problem.

There is uniform rod of weight W, leaning at an angle a from the vertical. It is fixed at the top and at the bottom.

Resolving W perpendicularly (p) and parallel (||) to the rod,

Wp = Wsin(a), W|| = Wcos(a)

Take moments about the bottom, then I get a force at the top acting perpendicularly to the rod of W/2 . sin(a).

Similary taking moments about the top, I get a force acting perpendicularly at the bottom, of W/2 . sin(a).

The || components at top and bottom at W/2 . cos(a).

Resolving vertically at the top & bottom, I get
Ftopv = W/2 . sin(a). sin(a) + W/2 . cos(a) .cos (a) = W/2
And the same for the bottom, which both add up neatly to W, as expected.

When I look at the horizontal components, I don't get a neat answer.

What should I get?

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