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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?
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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
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DENSITY USED IN PROFESSIONS
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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
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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
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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.
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The upper part (“crust”) is made of granite.
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The upper part of oceanic lithosphere is made of basalt.
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The continental lithosphere has a lower density than
oceanic lithosphere.
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When they meet, the higher density oceanic lithosphere is
forced to dive down into the Earth (“subduct”).
CONVERGENT BOUNDARIES
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The oceanic plate must “bend” downwards, so this
makes the ocean floor deeper.
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Where the two plates meet is a trench.
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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
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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
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WORKS CITED:
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http://www.green-planet-solar-energy.com/definition-of-density.html
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https://www.stevespanglerscience.com/lab/experiments/density-tower-magic-with-science
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http://www.ask.com/question/explaining-density-to-kids
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http://www.ask.com/question/why-is-density-important-in-life
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http://www.elcamino.edu/faculty/tnoyes/Readings/11A__R-Plate_Tectonics_Reading.pdf
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http://teacherweb.com/NJ/ValleyMiddleSchool-Oakland/DeRoker/why-density-is-important.pdf
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http://everydaylife.globalpost.com/can-study-density-used-real-world-41598.html
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https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcRWz8A485-yxj_GNggUNvcUAuP6dt2VYVg9yrVcO8Z_lUo3VQL
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http://chemwiki.ucdavis.edu/Analytical_Chemistry/Quantifying_Nature/Density_and_Percent_
Compositions
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https://www.grc.nasa.gov/www/k-12/airplane/Images/drageq.gif
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http://worldoceanreview.com/en/wor-1/climate-system/great-ocean-currents/