Concrete is the most common artificial composite material of all and typically consists of loose stones (aggregate) held with a matrix of cement. Concrete is a very robust material, much more robust than cement, and will not compress or shatter even under quite a large compressive force.
2) Y-axis contains absolute brightness Why do astronomers use the H-R Diagram? Astronomers use H-R Diagrams to classify stars and to understand how stars change over time.
This histogramâs horizontal (X) axis shows the luminance of the image from pure black on the left edge of the graph to pure white on the right edge. Growth on the vertical (Y) axis indicates the relative quantity of light for the given luminance.