Static equilibrium 3D, traffic light problem

J-dizzal · Jul 7, 2015

Homework Statement

The vertical and horizontal poles at the traffic-light assembly are erected first. Determine the additional force and moment reactions at the base O caused by the addition of the three 100-lb traffic signals B, C, and D. Report your answers as a force magnitude and a moment magnitude.

Diagram of a traffic-light support frame: a vertical pole rising from a square base O, with a horizontal arm holding three 100 lb signals labelled B, C and D. Segment lengths 20 ft, 20 ft and 31 ft are marked along the arms, with the x and y axes shown at the base.

Homework Equations

Sum of all forces and moments =0

The Attempt at a Solution

I got the Force at O right, but the moments I am not sure how to sum them

Handwritten free-body diagram of a 3D traffic-light pole assembly with X, Y and Z axes, showing three downward 100 lb forces and a worked equilibrium calculation: Ax = 0, Ay = 0, Az = 300 lb, Mx = 3100 ft-lb, My = -6000 ft-lb.

[/B]Edit: solved by finding magnitude of M

Dr. Courtney · Jul 7, 2015

You have two components of the moment vector. Compute the magnitude of the vector.

Static equilibrium 3D, traffic light problem

Homework Statement

Homework Equations

The Attempt at a Solution

Discussion

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