Question

The soil forces acting upon a mould board plough bottom resulting from the operations of cutting, pulverising, lifting, and inverting the furrow slice are 2.2 kN, 1.0 kN, and 0.8 kN along longitudinal, transverse, and vertical directions, respectively. The coefficient of soil-metal friction in the friction phase is 0.3. What will be the estimated draft, neglecting the effects of weight of the implement and the vertical reaction?

• A. 1460 N
• B. 1660 N
• C. 2440 N
• D. 2500 N

Hint:

Frictional force caused by the side force acts opposite to the direction of motion, directly adding to the longitudinal draft requirement:
\[ 2200\text{ N} + (0.3 \times 1000\text{ N}) = 2500\text{ N} \]

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The draft of a plough is the net horizontal force acting along the direction of travel.
Side forces acting perpendicular to travel create additional sliding friction on the landslide, which increases draft.

Step 2: Key Formula or Approach:
The total draft \(D\) consists of the direct longitudinal force \(L\) and the friction caused by the transverse (side) force \(T\):
\[ D = L + \mu T \]

Step 3: Detailed Explanation:
Given force components:
- Longitudinal force (\(L\)) = \(2.2\text{ kN} = 2200\text{ N}\)
- Transverse force (\(T\)) = \(1.0\text{ kN} = 1000\text{ N}\)
- Coefficient of soil-metal friction (\(\mu\)) = \(0.3\)
Calculate the longitudinal friction force opposing travel:
\[ F_{\text{friction}} = \mu \times T = 0.3 \times 1000\text{ N} = 300\text{ N} \] Calculate the total draft force \(D\):
\[ D = L + F_{\text{friction}} \] \[ D = 2200\text{ N} + 300\text{ N} = 2500\text{ N} \]

Step 4: Final Answer:
The correct option is 4, which corresponds to 2500 N.