Erosion - Natural Angle of Rest

Earth Science Unit Study - Angle of Rest
Week 35: We tested several different materials to determine their natural angles of rest.

The question - What are the characteristics of materials which have a big angles of rest, or will stack into the steepest hill. Hills of materials such as corn, sand, gravel and rock, each have a unique steepness. Some materials will stack nicely into a very steep hill, where as others will slide down until nearly flat.

We pulled several items from the kitchen cupboards to determine angle of rest following the procedure in How the Earth Works (How It Works).

First, the material was poured into a one cup container.

Next it was poured against a sheet of white paper held steady with a piece of cardboard, from a height of 8 inches.

Then the hill was sketched onto the white paper.

The base and top of the hill were marked with points, and the points were connected with a strait edge.

The angle of the hill was then measured with a protractor.

Then the process was repeated with many different substances.

The conclusion was the bigger and smoother the grains the flatter the hill. Flour stacked into the steepest hill, and both popcorn and pinto beans were nearly flat. Sunflower seeds and tapioca were in the middle.




This was a fun project and a great one to do in conjunction with a science fair. For more Earth Science project ideas, be sure to visit our Science Page.