Useful soil reaction forces acting on a tractor drawn mould board plough during operation are 2.0 kN, 0.9 kN and 0.6 kN along longitudinal, transverse and vertical directions, respectively. The soil-metal friction angle is 25°. Neglecting the effects of weight of the implement and the vertical soil reaction, the estimated draft in N is ______. [round off to one decimal place]
Official Answer Key:
2400.0 to 2440.0
Step-by-Step Solution & Explanation
With the vertical reaction and implement weight neglected, the draft (pull required along the direction of travel) is the longitudinal force plus the friction-induced component contributed by the transverse (side) soil reaction acting through the soil-metal friction angle: Draft = F_longitudinal + F_transverse·tan(φ) = 2000 + 900×tan(25°) = 2000 + 900×0.4663 = 2000 + 419.7 = 2419.7 N, within the accepted range.
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