For agricultural granular materials, the emptying angle of repose ($\theta_e$) and the filling angle of repose ($\theta_f$) are related such that:
Options:
(A) $\theta_e$ is generally slightly greater than or equal to $\theta_f$
(B) $\theta_f$ is always twice the emptying angle $\theta_e$
(C) $\theta_e$ is strictly zero for cereal grains
(D) The angle of repose is completely independent of grain moisture content
Answer Key:
A
Step-by-Step Solution & Explanation
During emptying (funnel flow discharge), the grains must overcome static interlocking and surface cohesion, causing the emptying angle of repose to be slightly larger than the filling (poured) angle of repose ($\theta_e \ge \theta_f$). Furthermore, angle of repose increases significantly with grain moisture content.