# How Do You Calculate the Weight of Signal C in a Suspended Cable System?

• jonnyboy
In summary, the problem involves determining the weight at signal C when it is suspended from a cable with a known weight at signal B. The solution involves using free body diagrams and solving for the tension in the shared cable between the two signals. However, the provided calculation results in a different answer than expected.
jonnyboy

## Homework Statement

Two traffic signals are temporarily suspended from a cable as shown. Knowing that the signal at B weighs 300N. Determine the weight at signal C.

## Homework Equations

Red arrows show lengths of cables and their components.
Answer is : W_c = 97.7N

## The Attempt at a Solution

I started by drawing two free body diagrams. One for particle B and the other for particle C. They both share the cable BC, hence, they share the same tension, T_bc, right? So, I tried to solve for T_bc with the free body diagram of particle B resulting in the sum of the forces along x: -T_ab(3.6/3.9) + T_bc(3.4/3.42) =0
(Sigma = addition of forces) SigmaF_y: T_ab(1.5/3.9) + T_bc(.4/3.42) - 300 = 0

So, solving for T_bc I get 251 N. I then follow the same steps as above for particle C.
I get Sigma F_x: T_bc(3.4/3.42) + T_cd(2.4/2.5) = 0
Sigma F_y: T_bc(.4/3.42) + T_cd(.7/2.5) - W_c = 0
so far? when I plug in what I got for T_bc to the second eqns. I get a different answer for w_c than what I'm supposed to get. please help

#### Attachments

• p1.bmp
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the free body diagram of particle B resulting in the sum of the forces along x: -T_ab(3.6/3.9) + T_bc(3.4/3.42) =0
simaF_y: T_ab(1.5/3.9) + T_bc(.4/3.42) - 300 = 0
So, solving for T_bc I get 251 N. I then follow the same steps as above for particle C.

Check this calculation. I am getting differenct answer.

I would suggest revisiting your calculations and equations to ensure accuracy. Additionally, it is important to consider all forces acting on particle C, including the weight of the signal itself and the tension in the cable BC. It may be helpful to draw a diagram and label all known and unknown forces, and then use the appropriate equations to solve for the weight at C. It is also important to double check your units and conversions to ensure consistency. If you are still having trouble, I would recommend seeking assistance from a teacher or tutor.

## 1. What is 2D Particle Equilibrium?

2D Particle Equilibrium is a concept in physics that describes the state of a system in which all forces acting on a particle are balanced, resulting in no acceleration or movement of the particle in any direction.

## 2. How is 2D Particle Equilibrium different from 1D Particle Equilibrium?

In 2D Particle Equilibrium, the forces acting on a particle are balanced in both the horizontal and vertical directions, whereas in 1D Particle Equilibrium, the forces are only balanced in one direction.

## 3. What are the key principles of 2D Particle Equilibrium?

The key principles of 2D Particle Equilibrium are the sum of all forces in the horizontal direction equals zero, the sum of all forces in the vertical direction equals zero, and the sum of all torques (rotational forces) equals zero.

## 4. How is 2D Particle Equilibrium applied in real-world scenarios?

2D Particle Equilibrium can be applied in various real-world scenarios, such as analyzing the forces acting on a bridge or determining the stability of a structure. It is also used in engineering and design to ensure that structures are able to withstand external forces without collapsing.

## 5. What are some common examples of 2D Particle Equilibrium?

Some common examples of 2D Particle Equilibrium include a book resting on a table, a person standing still on a level surface, and a ladder leaning against a wall without sliding or falling.

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