Question: Discuss the relationship between the internal friction angle and the angle of repose in soils or granular materials. Provide the analysis, discussion and conclusion, thank you!

Analysis and Discussion:

$-$Analyze how and why the angle of repose can serve as an approximation for the internal friction angle.

$-$Discuss limitations and factors $($like particle size, moisture content, or shape$)$ that could affect the accuracy of this relationship.

Conclusion:

$-$Summarize the findings and reflect on the practical applications of understanding this relationship in engineering fields.