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DENSITY Amber Fain Amber Hutson Kylie Ford EMPACTS Project, Spring 2014 Introduction to Physical Science for Teachers C. Dianne Phillips, Instructor WHAT IS DENSITY? Density of a material is its mass per unit volume. The simplest way is by comparing the difference in the weight of two different objects of the same size Things with less density will float and things with a higher density will sink Density is the ratio of the mass of a substance to its volume WHY IS DENSITY RELEVENT: Density is similar to buoyancy, and buoyancy is needed for ships and boats to float All objects have a density which decides whether they will sink or float Density is a physical property of matter that describes how compact a substance is DENSITY USED IN PROFESSIONS Engineers understand the concept of density when planning to build anything where weight and distribution of weight are critical. Engineers use to build ships and aircrafts. Airplane Weight Distribution is used to know how much weight they need and how much space they should allot for certain kind of weight. Plumbing Systems use density-Fluid flowing through a pipe is an important real-world application of density governed by a relation known as Bernoulli's equation. All else being equal, a fluid of greater density will flow through a pipe with a lower pressure, velocity, or height, respectively. Engineers rely on Bernoulli's equation when they design dams and large-scale plumbing projects. THE LITHOSPHERE AND DENSITY The lithosphere is made up of two parts. The upper part is made of lower density, Lighter colored granite or higher density, Darker colored basalt. The lower part is made of solidified mantle rock. The bedrock of the continents is made of granite while the ocean floor is made of basalt, so continental lithosphere has a lower density than oceanic lithosphere. EX. CONVERGENT BOUNDARIES Convergent boundaries are places where plates are coming together (“colliding”) or “converging.” There are three kinds of convergent boundaries: where oceanic lithosphere meets continental lithosphere, where oceanic lithosphere meets oceanic lithosphere, and where continental lithosphere meets continental lithosphere. The upper part (“crust”) is made of granite. The upper part of oceanic lithosphere is made of basalt. The continental lithosphere has a lower density than oceanic lithosphere. When they meet, the higher density oceanic lithosphere is forced to dive down into the Earth (“subduct”). CONVERGENT BOUNDARIES The oceanic plate must “bend” downwards, so this makes the ocean floor deeper. Where the two plates meet is a trench. As the oceanic plate dives down into the Earth, it melts, creating low density magma which rises up beneath the other plate. The subducting plate melts and the molten material rises and mixes as it also melts continental lithospheric rocks. More and more lava comes up, cools, and piles up, forming volcanic mountains at the edge of the continent THE PROCESS – DENSITY DRIVEN HYPOHYALINE CYCLES DENSITY DRIVEN CONVECTION Waters density varies depending on salinity and temperature Cold, salty water is heavy and sinks to great depths This causes the circulation of millions of cubic meters of water in the ocean This occurs in a few polar regions of the ocean and is called convection The surface water in the North Atlantic region sinks to a depth of around 2000 meters due to convection There it settles on an even denser deep-water layer from the Antarctic that extends down to the sea floor DENSITY AND THE GLOBAL CONVEYER BELT http://www.youtube.com/watch?v=XVZuj RMGZzs DENSITY DRIVEN CONVECTION Low temperature and high salinity are the primary driving forces of convection They pull the dense water of the polar regions downward This drives a worldwide convection engine called thermohaline circulation (thermo – driven by temperature differences; haline – driven by salinity differences) Convection only occurs locally in the polar regions, it propels thermohaline circulation, which spans the globe like a giant conveyor belt WORKS CITED: o http://www.green-planet-solar-energy.com/definition-of-density.html o https://www.stevespanglerscience.com/lab/experiments/density-tower-magic-with-science o http://www.ask.com/question/explaining-density-to-kids o http://www.ask.com/question/why-is-density-important-in-life o http://www.elcamino.edu/faculty/tnoyes/Readings/11A__R-Plate_Tectonics_Reading.pdf o http://teacherweb.com/NJ/ValleyMiddleSchool-Oakland/DeRoker/why-density-is-important.pdf o http://everydaylife.globalpost.com/can-study-density-used-real-world-41598.html o https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcRWz8A485-yxj_GNggUNvcUAuP6dt2VYVg9yrVcO8Z_lUo3VQL o http://chemwiki.ucdavis.edu/Analytical_Chemistry/Quantifying_Nature/Density_and_Percent_ Compositions o https://www.grc.nasa.gov/www/k-12/airplane/Images/drageq.gif o http://worldoceanreview.com/en/wor-1/climate-system/great-ocean-currents/