Stress describes the force applied to a material (per unit area) from an external source, permanent deformations in the materials, and/or uneven heating. It has the units [Pascals]. Normal Stress is the stress applied normal to the face of the material. If the normal stress results in a decreasing of the axial length of the material it is called compressive stress, and if the axial length increases it is called tensile stress. If the normal stress is applied everywhere on the…
Plate Tectonics is the process of creating new crust at mid-ocean ridges and recycling older, denser crust back into the interior at subduction zones. Subduction is driven by two main mechanical processes: slab-pull and ridge-push. RIDGE PUSH High ridges are produced by the positive buoyancy of material in regions of localized heating. Ridge-push utilizes the potential energy of the height of these ridges to force slabs to subduct. SLAB-PULL Slab-pull depends on the negative buoyancy of the cold subducting slab to pull itself deeper into…
X-RAY POWDER DIFFRACTION is a process of identifying the crystal structure (i.e. atomic spacing) of a powder sample using x-rays. It can tell you both what elements are present as well as differentiating between polymorphs. PRODUCING X-RAYS Electrons are freed from a tungsten filament (aka cathode) by heating, where the valence electrons are free to move with very little energy input. Normally the electrons would stay within the metal because it becomes (+) charged when the electrons leave, drawing them…
The Rossby Number describes the importance of the rotation of the frame on the flow. It is the ratio of the inertial force (e.g. buoyancy) of the fluid to the Coriolis force imposed by rotation. A larger Rossby number will mean the flow’s behavior is less dependent on the rotation. where describes the typical magnitude of the horizontal flow components, is the rotation rate, is the latitude of the fluid parcel on a sphere (e.g. Earth), f is the…
Gas Chromatography is a method of analyzing an unknown liquid mixture by separating the components by boiling point 1. A liquid mixture of unknown compounds A and B is injected into a column with an inert gas (usually Helium) which pushes the liquid through the column into an oven (brown) where it vaporizes 2. The column is coated with a liquid with a high boiling point (green). The gas with the higher boiling point (B) will form stronger bonds with…