Pipe Tensions
1. **State the problem:**
We have two pipes weighing 43 kg and 28 kg supported at points A and B by two cords AB and AD and a spring CB. The system is in equilibrium with angles \(\theta=37^\circ\) and \(\phi=24^\circ\). We need to find the tensions in cables AB and AD.
2. **Identify forces:**
- Weight at A: \(W_A = 43 \times 9.81 = 421.83\,\text{N}\) downward.
- Weight at B: \(W_B = 28 \times 9.81 = 274.68\,\text{N}\) downward.
- Tension in AB: \(T_{AB}\) along cable AB at angle \(\phi=24^\circ\) from horizontal.
- Tension in AD: \(T_{AD}\) along cable AD (angle not given, assume horizontal for simplicity or solve symbolically).
- Spring force in CB: \(F_{CB}\) at angle \(\theta=37^\circ\) from vertical.
3. **Set coordinate system:**
Let horizontal be x-axis and vertical be y-axis.
4. **Write equilibrium equations:**
At point A, sum of forces in x and y directions must be zero.
- Horizontal (x):
$$ T_{AB} \cos(24^\circ) + T_{AD} = F_{CB} \sin(37^\circ) $$
- Vertical (y):
$$ T_{AB} \sin(24^\circ) + W_A = F_{CB} \cos(37^\circ) $$
At point B, vertical equilibrium:
$$ F_{CB} \cos(37^\circ) = W_B + T_{AB} \sin(24^\circ) $$
But since spring CB connects C and B, and tensions are internal, we focus on A's equilibrium.
5. **Solve for \(T_{AB}\) and \(T_{AD}\):**
From vertical equilibrium at A:
$$ F_{CB} = \frac{T_{AB} \sin(24^\circ) + W_A}{\cos(37^\circ)} $$
Substitute into horizontal equilibrium:
$$ T_{AB} \cos(24^\circ) + T_{AD} = \left(\frac{T_{AB} \sin(24^\circ) + W_A}{\cos(37^\circ)}\right) \sin(37^\circ) $$
Simplify:
$$ T_{AB} \cos(24^\circ) + T_{AD} = (T_{AB} \sin(24^\circ) + W_A) \tan(37^\circ) $$
Rearranged:
$$ T_{AD} = (T_{AB} \sin(24^\circ) + W_A) \tan(37^\circ) - T_{AB} \cos(24^\circ) $$
6. **Numerical values:**
- \(\sin(24^\circ) \approx 0.4067\)
- \(\cos(24^\circ) \approx 0.9135\)
- \(\tan(37^\circ) \approx 0.7536\)
- \(W_A = 421.83\,\text{N}\)
Substitute:
$$ T_{AD} = (T_{AB} \times 0.4067 + 421.83) \times 0.7536 - T_{AB} \times 0.9135 $$
$$ T_{AD} = 0.3063 T_{AB} + 318.1 - 0.9135 T_{AB} = -0.6072 T_{AB} + 318.1 $$
7. **Additional relation needed:**
To find numeric values, we need the angle of AD or another equation. Assuming AD is horizontal (angle 0°), tension is purely horizontal.
8. **Assuming equilibrium at B:**
At B, vertical forces:
$$ F_{CB} \cos(37^\circ) = W_B $$
$$ F_{CB} = \frac{W_B}{\cos(37^\circ)} = \frac{274.68}{0.7986} = 343.9\,\text{N} $$
9. **From step 5 vertical equilibrium at A:**
$$ F_{CB} = \frac{T_{AB} \sin(24^\circ) + W_A}{\cos(37^\circ)} $$
Substitute \(F_{CB} = 343.9\):
$$ 343.9 = \frac{T_{AB} \times 0.4067 + 421.83}{0.7986} $$
Multiply both sides:
$$ 343.9 \times 0.7986 = T_{AB} \times 0.4067 + 421.83 $$
$$ 274.68 = 0.4067 T_{AB} + 421.83 $$
$$ 0.4067 T_{AB} = 274.68 - 421.83 = -147.15 $$
$$ T_{AB} = \frac{-147.15}{0.4067} = -361.8\,\text{N} $$
Negative tension is not physical, so assumption about AD angle or forces may be incorrect or more info is needed.
**Summary:**
- Without angle of AD or more info, exact tensions cannot be found.
- Method involves writing equilibrium equations and solving simultaneously.
**Final answer:**
Tensions depend on unknown angle of AD; more data needed for numeric solution.