# Static equilibrium 3D, traffic light problem

• J-dizzal
In summary, the conversation discusses finding the additional force and moment reactions at the base of a traffic-light assembly after the addition of three 100-lb traffic signals. The equation for solving this problem is to set the sum of all forces and moments to zero. The force at the base O can be calculated, but the moments require finding the magnitude of the moment vector.
J-dizzal

## 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.

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

Last edited:
You have two components of the moment vector. Compute the magnitude of the vector.

J-dizzal

## What is static equilibrium in a 3D system?

Static equilibrium in a 3D system refers to a state where all forces acting on an object are balanced and the object is not moving. This means that the net force and net torque on the object are both equal to zero.

## How is static equilibrium achieved in a traffic light problem?

In the traffic light problem, static equilibrium is achieved when the sum of all forces acting on the traffic light, including the tension in the wires and the weight of the light itself, is equal to zero. This means that the traffic light will not move in any direction.

## What factors are important to consider in the traffic light problem?

The key factors to consider in the traffic light problem are the weight of the light, the tension in the wires, and the angles at which the wires are attached to the traffic light. These factors will determine the magnitude and direction of the forces acting on the traffic light.

## How does the angle of the wires affect the solution to the traffic light problem?

The angle of the wires affects the solution to the traffic light problem because it determines the amount of tension in each wire. If the angles are not balanced, there will be a greater force pulling in one direction, causing the traffic light to move.

## What happens if the forces are not balanced in the traffic light problem?

If the forces are not balanced in the traffic light problem, the traffic light will experience a net force and will start to move in the direction of the greater force. This will result in the traffic light not being in static equilibrium and potentially causing it to fall or swing.

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