WATER PROPERTIES
www.pwssc.org
Why do we want to explore the
ocean?
 The Oceans are the number one driver of weather
and climate
 They are also important for transportation and food
 To learn about the organisms that live there
 Almost every type of plant and animal known to
science can be found in the ocean
www.pwssc.org
What is it like underwater?
 Dark
 Deep
 Lots of pressure
 Big
 Cold
 Salty
www.pwssc.org
Three Properties of
Water
• Density
• Pressure
• Buoyancy
www.pwssc.org
Density
 How much “stuff” is in a certain amount of “space”
𝑀𝑎𝑠𝑠
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =
𝑉𝑜𝑙𝑢𝑚𝑒
 Mass is the amount of matter (stuff) in an object.
 Volume is the amount of space an object takes up.
www.pwssc.org
Density Example
 A rock and a crumpled piece of paper are the same
size. They have the same Volume.
 The rock weighs more than the piece of paper, it has
greater Mass.
𝑀𝑎𝑠𝑠
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =
𝑉𝑜𝑙𝑢𝑚𝑒
 Which item has a greater Density?
www.pwssc.org
Density and States of Matter
Solid
Liquid
Gas
Density refers to how closely "packed" or "crowded" the
material appears to be
www.pwssc.org
http://www.cofc.edu/~martine/111Lect
Week1_files/image008.jpg
Pressure
 How much force is applied to an area.
 Measured in Pascals (Pa), atmospheres (ATM), or
pounds per square inch (psi)
 There are many other units as well!
 Water pressure is caused by the weight of water
pressing down on what is beneath it.
 The deeper you go, the more water is above you, the
greater the pressure.
𝐹𝑜𝑟𝑐𝑒
𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 =
𝐴𝑟𝑒𝑎
www.pwssc.org
Water Pressure
 Water and air are both fluids.
 Water is more dense than air, so it “sinks.”
 In a bottle with half air and half water the water stays
at the bottom.
www.pwssc.org
Units of Pressure
 At sea level the pressure is equal to:
 101,325 Pa
 14.7 psi
 1 ATM
 Our bodies are used to this level of pressure, they
exert the same amount of pressure back.
 Underwater
 10 meters (33 feet) of water above you will exert 1 ATM
of pressure
www.pwssc.org
Water Pressure
 This Styrofoam cup was
sent to 1279 m and felt
1833 psi or 125
atmospheres of pressure
 Why caused the cup to
get smaller?
 Has the density of the
cup changed?
www.pwssc.org
http://iodp.tamu.e
du/scienceops/gall
ery/exp311/week7/
pages/exp311_107.
html
High Pressure Adaptations
Animals that live in the deep
have adapted to a high
pressure environment.
 No excess cavities
 Soft, pliable bones
http://ocean.nationalgeographic.com/ocean/
photos/deep-sea-creatures/
www.pwssc.org
Buoyancy
 The ability of something
to float in a fluid (water,
air, etc.)
 Archimedes Principle:
An object is buoyed up
by a force equal to the
weight of the fluid
displaced by the object.
www.pwssc.org
http://en.wikipedia.org/wiki/Image:Buoyancy.svg
States of Buoyancy
 Positive Buoyancy (float) The weight of the object
is less than the weight of the displaced water.
 Negative Buoyancy (sink) The weight of the object
is MORE than the weight of the displaced water.
 Neutral Buoyancy (hover) The weight of the object
is the SAME as the weight of the water displaced.
www.pwssc.org