- #1
Pascal1p
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Homework Statement
This is the question, but with me 6 kN/m is 4 kN/m and 2 kN/m is 2.5 kN/m.
I am not yet at the chapter of equations of equilibrium, plus it says the couple moment is not 0, so I assume it just about the loadings and not including the reactive forces and reactive moment.
Homework Equations
F= 1/2*b*h
M= 1/2*b*h*d
The Attempt at a Solution
So if I call the top one F1 and the bottom loading F2 I got:
F1+F2=0= -4*b*1/2+2.5*(b+a)*1/2
solving this i got a=0.6b
Moment around the of the bar (not A, but opposite side) due to the loadings is (counter clockwise positive):
M= -F1*center of triangle + F2*center of triangle
Because you can replace the loading with force F1 and force F2 and its line of action is through the center of the triangle area (1/3* base)
M= -8= -4*b*1/2*1/3b+2.5*(b+a)*1/2*1/3*(b+a)
So what am I doing wrong?
Because M can never be negative with me, plus the answer should be b= 5.625 and a= 1.539.
But this to me makes no sense, because then F1+F2 is not 0.
And if I should take the reactive forces into account at A then you can never have still a moment, because then it is not static anymore.