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.
F = (Fx, Fy). Graphically it is represented by an arrow pointing along a line that makes an angle of f=30o with the x-axis. The length of the arrow is proportional to the magnitude of the force. The projections of this arrow onto the x- and y-axes represent the x- and y-components of the force. In spherical coordinates a vector is specified by its length and the angles the vector makes with the x- and z-axis.