A 3-bottom tractor-drawn mouldboard plough with a cutting width of $30\text{ cm}$ per bottom operates at a plowing depth of $15\text{ cm}$. If the specific draft of the soil is $0.50\text{ kg/cm}^2$, the total draft required to pull the plough in $\text{kN}$ (taking $g = 9.81\text{ m/s}^2$) is ________ (round off to 2 decimal places).
Answer Key:
6.62
Step-by-Step Solution & Explanation
1. Total furrow cross-sectional area $A$:
$A = n \times w \times d = 3 \times 30\text{ cm} \times 15\text{ cm} = 1350\text{ cm}^2$
2. Total draft force in $\text{kgf}$:
$D_{\text{kgf}} = A \times \text{Specific Draft} = 1350\text{ cm}^2 \times 0.50\text{ kg/cm}^2 = 675\text{ kgf}$
3. Convert to $\text{kN}$:
$D = \frac{675 \times 9.81}{1000} = 6.62175\text{ kN} \approx 6.62\text{ kN}$