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Moment about a point

  • #1

Homework Statement


A 100 lb vertical force is applied to the end of a lever, which is attached to a shaft at O. Determine (a) the moment of the 100 lb force about O (b) the horizontal force applied at a that creates the same moment about O.

Homework Equations




The Attempt at a Solution


I know the solution but I'm still a bit confused as to what I'm doing for part (a) I have Mo = Fd = 24in*cos(60) * 100 lb
But I don't understand why I'm using
24in*cos(60) and not 24in*sin(60)....

2duxg01.jpg
 

Answers and Replies

  • #2
Doc Al
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But I don't understand why I'm using
24in*cos(60) and not 24in*sin(60)....
You need the perpendicular distance between O and the line of action of the force.
 

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