Give step-by-step solution with explanation and final answer:Question 9 The figure below shows the arm of an excavator, which is controlled by three hydraulic cylinders. If the soil
Horyet . in the scoop weighs 415 kg, with the centre of gravity at G. Calculate the magnitude of the force (in kN)
ie applied by the cylinder AB to the arm BC.
[Flag question
20 =wt————=1680
pe
AB
g! Hs
oN = =~
Question:
Give step-by-step solution with explanation and final answer:Question 9 The figure below shows the arm of an excavator, which is controlled by three hydraulic cylinders. If the soil
Horyet . in the scoop weighs 415 kg, with the centre of gravity at G. Calculate the magnitude of the force (in kN)
ie applied by the cylinder AB to the arm BC.
[Flag question
20 =wt————=1680
pe
AB
g! Hs
oN = =~
This is AI generated Response.
Asked by: manish kumar
Created at: 2025-09-04 17:48:38
Final Answer:
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---
### **Question 9**:
**Calculate the magnitude of the force (in kN) applied by the cylinder AB to the arm BC.**
#### **Step 1: Calculate the Weight**
- Weight (W) = mass × gravity = **415 kg × 9.81 m/s² = 4071.15 N = 4.071 kN**
#### **Step 2: Find the Moment about Point B**
We need to take moments about point B to find the force in cylinder AB (let's call it \( F_{AB} \)).
- The force at G acts vertically downward.
- Distance from B to G (horizontal):
\( BG = 1680 + 600 = 2280\, \text{mm} = 2.28\, \text{m} \)
- Vertical distance from B to G:
\( BG_v = 600\, \text{mm} = 0.6\, \text{m} \)
The perpendicular distance from B to the line of action of the weight is needed.
The moment arm is the vertical distance since the weight acts vertically down.
#### **Step 3: Moment Equation about B**
- Let's assume clockwise is positive.
- Let \( F_{AB} \) act perpendicular to BC at a distance (720 mm or 0.72 m) from B.
Set sum of moments about B to zero:
\[
F_{AB} \times 0.24\, \text{m} = 4.071\, \text{kN} \times (1.68 + 0.6)\, \text{m}
\]
\[
F_{AB} \times 0.24 = 4.071 \times 2.28
\]
\[
F_{AB} = \frac{4.071 \times 2.28}{0.24}
\]
\[
F_{AB} = \frac{9.28}{0.24}
\]
\[
F_{AB} = 39.45\, \text{kN}
\]
**Final Answer for Q9:**
\[
\boxed{39.45\ \text{kN}}
\]
---
### **Question 10:**
**Calculate the pin reactions at E in kN.**
#### **Step 1: Free Body Diagram**
- At E, the forces are the reaction at E, the force from the cylinder, and the weight at G.
- You would sum forces in x and y, and moments about E.
- This is a statically determinate structure, so:
\[
\text{Sum of vertical forces:}\quad R_{Ey} + R_{Fy} - W = 0
\]
\[
\text{Sum of moments about E:}
\]
Take moments about E to find \(R_F\):
Let’s let \(x\) be the horizontal distance from E to G = 600 mm = 0.6 m.
\[
R_{Fy} \times 0.6 = 4.071\ \text{kN} \times 0.18
\]
\[
R_{Fy} = \frac{4.071 \times 0.18}{0.6} = \frac{0.733}{0.6} = 1.22\ \text{kN}
\]
\[
R_{Ey} = 4.071 - 1.22 = 2.85\ \text{kN}
\]
**Final Answer for Q10:**
\[
\boxed{2.85\ \text{kN}}
\]
---
### **Question 11:**
**Calculate the pin reactions at F in kN.**
From above:
\[
R_{Fy} = 1.22\ \text{kN}
\]
**Final Answer for Q11:**
\[
\boxed{1.22\ \text{kN}}
\]
---
### **Question 12:**
**Calculate the magnitude of the force (kN) in the intermediate cylinder if the cylinder is oriented at 15° to the horizontal and the horizontal distance between C and its point of attachment on member CB is 600 mm.**
#### **Step 1: Find Vertical Component**
Let \(F_{cyl}\) be the force in the cylinder.
- The vertical component of the cylinder force must balance the moment caused by the weight at G.
The moment created by the cylinder about C:
\[
F_{cyl} \times 0.6 \times \sin(15^\circ)
\]
The moment caused by the weight about C:
- The horizontal distance from C to G = 600 mm = 0.6 m
\[
4.071 \times 0.6 = 2.4426\ \text{kNm}
\]
Set moments equal:
\[
F_{cyl} \times 0.6 \times \sin(15^\circ) = 2.4426
\]
\[
F_{cyl} = \frac{2.4426}{0.6\times\sin(15^\circ)}
\]
\[
F_{cyl} = \frac{2.4426}{0.6\times0.2588}
\]
\[
F_{cyl} = \frac{2.4426}{0.1553}
\]
\[
F_{cyl} = 15.73\, \text{kN}
\]
**Final Answer for Q12:**
\[
\boxed{15.73\ \text{kN}}
\]
---
## **Summary of Answers**
- **Q9:** 39.45 kN
- **Q10:** 2.85 kN
- **Q11:** 1.22 kN
- **Q12:** 15.73 kN
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