The figure below shows a beam with a cable attached to the right-hand end of the beam and
it passes over a frictionless pulley which carries a mass of 50 kg. The beam also carries a
uniformly distributed load of 8 kN/m. The left-hand support (A) is a fixed support, and the right-
hand support (B) is a roller support. The weight of the beam can be ignored. Calculate the
magnitude and direction of the reactions at supports A and B, answers must be in kN.
Highlight answers
8kN/m . Q
Al EH HTT
Gy S0kg
A B
8m
— l—2m |
Question:
The figure below shows a beam with a cable attached to the right-hand end of the beam and
it passes over a frictionless pulley which carries a mass of 50 kg. The beam also carries a
uniformly distributed load of 8 kN/m. The left-hand support (A) is a fixed support, and the right-
hand support (B) is a roller support. The weight of the beam can be ignored. Calculate the
magnitude and direction of the reactions at supports A and B, answers must be in kN.
Highlight answers
8kN/m . Q
Al EH HTT
Gy S0kg
A B
8m
— l—2m |
This is AI generated Response.
Asked by: Test User 100227
Created at: 2025-05-18 20:26:03
Final Answer:
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Let's break down the problem step by step:
### 1. **Identify Loads and Reactions**
#### **Loads:**
- **Uniformly distributed load (UDL):**
\( w = 8\, \text{kN/m} \) over \( 8\, \text{m} \)
Total load = \( 8 \times 8 = 64\, \text{kN} \)
Acts at the center of the 8 m section, i.e., 4 m from A.
- **Point load due to 50 kg mass:**
Weight \( W = mg = 50 \times 9.81 = 490.5\, \text{N} = 0.491\, \text{kN} \)
This acts vertically downward at the right end (distance = 12 m from A).
The cable forms an angle of \( 120^\circ \) with the beam, so the force in the cable (\( T \)) is:
- Vertical component \( T_v = T \sin(120^\circ) \)
- Horizontal component \( T_h = T \cos(120^\circ) \)
#### **Reactions:**
- **At A (fixed support):** \( A_x \), \( A_y \), and moment \( M_A \)
- **At B (roller):** \( B_y \) (vertical only)
---
### 2. **Equilibrium Equations**
#### **Sum of Forces in X direction:**
\[
\sum F_x = 0: \quad A_x + T \cos(120^\circ) = 0
\]
#### **Sum of Forces in Y direction:**
\[
\sum F_y = 0: \quad A_y + B_y - 64 - T \sin(120^\circ) = 0
\]
#### **Sum of Moments about A:**
Take moments about point A (clockwise positive):
- UDL: \( 64\, \text{kN} \) acts at 4 m from A.
- \( B_y \) acts at 10 m from A.
- The vertical component of the cable (\( T_v \)) acts at 12 m from A.
\[
\sum M_A = 0: \quad
-64 \times 4 + B_y \times 10 + [T \sin(120^\circ)] \times 12 = 0
\]
---
### 3. **Calculate Cable Force \( T \):**
\[
T = 0.491\, \text{kN}
\]
\[
\sin(120^\circ) = 0.866, \quad \cos(120^\circ) = -0.5
\]
\[
T_v = T \sin(120^\circ) = 0.491 \times 0.866 = 0.425\, \text{kN}
\]
\[
T_h = T \cos(120^\circ) = 0.491 \times (-0.5) = -0.246\, \text{kN}
\]
---
### 4. **Solve for Unknowns**
#### **Moment about A:**
\[
-64 \times 4 + B_y \times 10 + 0.425 \times 12 = 0
\]
\[
-256 + 10B_y + 5.1 = 0
\]
\[
10B_y = 256 - 5.1 = 250.9
\]
\[
\boxed{B_y = 25.09\, \text{kN}\ \uparrow}
\]
---
#### **Sum of Vertical Forces:**
\[
A_y + B_y - 64 - 0.425 = 0
\]
\[
A_y + 25.09 - 64 - 0.425 = 0
\]
\[
A_y = 64 + 0.425 - 25.09 = 39.335\, \text{kN}
\]
\[
\boxed{A_y = 39.34\, \text{kN}\ \uparrow}
\]
---
#### **Sum of Horizontal Forces:**
\[
A_x + T_h = 0
\]
\[
A_x - 0.246 = 0
\]
\[
\boxed{A_x = 0.246\, \text{kN}\ \rightarrow}
\]
---
### **Final Highlighted Answers**
#### **Reactions at Supports:**
- **At A:**
- \( \boxed{A_x = 0.25\ \text{kN}\ \rightarrow} \)
- \( \boxed{A_y = 39.34\ \text{kN}\ \uparrow} \)
- **At B:**
- \( \boxed{B_y = 25.09\ \text{kN}\ \uparrow} \)
Let me know if you need the moment at A or a summary table!
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