I\'m going to rewrite the problem statement above for those who cannot read it.

Question

I'm going to rewrite the problem statement above for those who cannot read it.

"The rectangular plate is made up of 1.7-ft squares as shown. A 29-lb force is applied at point A in the direction shown. Calculate the moment MB of the force about point B by atleast two different methods. Your answer will be positive if counterclockwise, negative if clockwise."

I have tried using the following formulas to find the answer:

M=r x F

M=F*r*sin(alpha)

The direction I found was clockwise, so my answer should be negative. That much I worked out without too much trouble.

With the first formula I got this:

F= 29*cos(33.69)i + 29*sin(33.69)j

= 24.1295i + 16.0863j

r = 1.7i +6.8j

r x F = M = -139.14684

With the second formula I got this:

F = 29 lb

r = 7.093 ft

Alpha = 42.27 degrees

M = 29*7.093*sin(42.27)

= 138.357

These are both wrong. If you could work it out for me, I would appreciate it.

Explanation / Answer

Use this formula. M = F x d , m-moment, F-force, d -distance Note: All forces must be parallel in either direction (opposite or same direction) and must be perpendicular to the body. Body means material under analysis. ie. beam, column, etc.

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