According to V.P. Gorjatchkin's classical rational three-term draft equation for a mouldboard plough ($D = f G + k a b + \epsilon a b v^2$), which of the following statements is/are CORRECT?
Options:
(A) The term $f G$ accounts for friction and rolling resistance between the plough bottom and the furrow floor
(B) The term $k a b$ represents the static resistance required to deform and slice the soil cross-section of width $b$ and depth $a$
(C) The term $\epsilon a b v^2$ represents the dynamic kinetic energy transferred to accelerate and throw the furrow slice
(D) The coefficient $\epsilon$ decreases dramatically as forward speed increases
Answer Key:
A, B, C
Step-by-Step Solution & Explanation
- **A is correct:** $f G$ is the passive friction resistance of the plough weight $G$ sliding across soil.
- **B is correct:** $k a b$ represents useful soil cutting and deformation work, where $k$ is the specific soil resistance (static component).
- **C is correct:** $\epsilon a b v^2$ accounts for the dynamic throwing and acceleration of soil particles, varying with the square of velocity $v^2$.
- **D is incorrect:** The parameter $\epsilon$ is an empirical shape coefficient dependent on mouldboard curvature and soil density; it is treated as a constant, not decreasing with speed.