# 3D Rigid Body Equilibrium

1. May 8, 2014

### KiltedEngineer

1. The problem statement, all variables and given/known data

The rod assembly shown has a ball-and-socket joint at A and a smooth journal bearing at C. The forces F1=600N , F2=410N , F3=460N , and F4=950N are applied as shown in the figure. The geometry of the rod assembly is given as a=0.900m , b=0.650m , and c=0.800m. Neglect the weight of the rod. The journal bearing supports the rod in such a manner that it is free to rotate about the y axis.

1.)Determine the magnitude of the y component of the reaction at C

2.) Determine the magnitude of the z component of the reaction exerted on the rod at C.

3.) Determine the magnitude of the z component of the reaction on the rod at B.

4.) Determine the magnitude of the x component of the reaction on the rod at B.

5.) Determine the magnitude of the z component of the reaction on the rod at A

6.) Determine the magnitude of the x component of the reaction on the rod at A

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2. May 9, 2014

### paisiello2

You have 6 unknown reaction forces and 6 equilibrium equations. Can you set those up?

3. May 9, 2014

### PhanthomJay

When summing moments = 0, sum about axes, not points. Like
Sum of moments about z axis = sum of F_x(y) + F_y(x) , where y and x are the perpendicular distances from the line of action of F_x and F_y respectively, to the z axis. Etcetera for other axes with appropriate subscripts. 7 hours, those were the days my friend I'd thought they'd never end....