Cable Tension Length 0E03Cc
1. **Problem Statement:**
Determine the tension in each segment of the cable ($F_{BA}$, $F_{BC}$, $F_{CD}$) and the total length of the cable.
2. **Equations of Equilibrium:**
At joint B:
$$\sum F_x = 0: F_{BC} \cos \theta - F_{BA} \frac{4}{\sqrt{65}} = 0 \quad [1]$$
$$\sum F_y = 0: F_{BA} \frac{7}{\sqrt{65}} - F_{BC} \sin \theta - 50 = 0 \quad [2]$$
At joint C:
$$\sum F_x = 0: F_{CD} \cos \phi - F_{BC} \cos \theta = 0 \quad [3]$$
$$\sum F_y = 0: F_{BC} \sin \theta + F_{CD} \sin \phi - 100 = 0 \quad [4]$$
3. **Geometry and Angles:**
$$\sin \theta = \frac{y}{\sqrt{y^2 + 25}}, \quad \cos \theta = \frac{5}{\sqrt{y^2 + 25}}$$
$$\sin \phi = \frac{3 + y}{\sqrt{y^2 + 6y + 18}}, \quad \cos \phi = \frac{3}{\sqrt{y^2 + 6y + 18}}$$
4. **Substitution and Solution:**
Substitute the trigonometric expressions into the equilibrium equations [1]-[4] and solve the system for $F_{BA}$, $F_{BC}$, $F_{CD}$, and $y$.
Given solution:
$$F_{BC} = 46.7, \quad F_{BA} = 83.0, \quad F_{CD} = 88.1, \quad y = 2.679$$
5. **Total Cable Length:**
Calculate the length of each segment:
$$l = \sqrt{7^2 + 4^2} + \sqrt{5^2 + 2.679^2} + \sqrt{3^2 + (2.679 + 3)^2}$$
Calculate each term:
$$\sqrt{49 + 16} = \sqrt{65} \approx 8.062$$
$$\sqrt{25 + 7.176} = \sqrt{32.176} \approx 5.672$$
$$\sqrt{9 + 32.176} = \sqrt{41.176} \approx 6.466$$
Sum:
$$l = 8.062 + 5.672 + 6.466 = 20.2$$
**Final answers:**
- Tensions: $F_{BA} = 83.0$, $F_{BC} = 46.7$, $F_{CD} = 88.1$ (all in lb)
- Total cable length: $20.2$ ft