Heat and Density

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Heat and Density

• Which heats faster sand or water?

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Heat and Density

• Ever feel the hot sand on your feet?
• Cant wait to get your feet in the water?
• Why is the sand so hot and the water cool?

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Heat and Density

• Density the concentration of matter in an
  object
• Density can also be considered the amount of
  something in a specified volume or area.
• Density mass(g)/volume(cm3)

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Heat and Density

• The formal definition of density is mass per unit
  volume. Usually the density is expressed in
  grams per mL or cc. Mathematically a per
  statement is translated as a division problemcc
  is a cubic centimeter and is equal to a mL.

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Heat and Density

• In order to determine the density of an object or
  substance, it is necessary to know the mass, the
  volume of the substance, and the definition of
  density.
• http//www.elmhurst.edu/chm/vchembook/120Adensity
  .html

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Heat and Density

• Ocean water has a higher density than fresh
  water.
• Ocean water contains many dissolved substances
  and these add mass to the water within which they
  are dissolved, thereby producing a greater mass
  per unit volume, or a density, higher than that
  of pure water.

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Heat and Density

• The density of ocean water depends on salinity,
  temperature, and pressure.
• At constant temperature and pressure, density
  varies with salinity.
• Density and temperature have an indirect
  (inverse) relationship. As temperature increases
  density decreases. If temperature decreases,
  density increases.

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HEAT and Density

• Density has a direct relationship with both
  pressure and salinity. As pressure and/or
  salinity increases density increases.

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Heat and Density

• Objectives
• Predict which substance will heat more
  quicklywater or sand.
• Observe changes in temperature of the two
  substances when heated.
• Make inferences concerning the density of
  substances based upon how easily the substance
  absorbs and releases heat.

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Heat and Density

• Objectives (continued)
• Compare predictions prior to the experiment to
  the actual outcome.
• Record and interpret data and reactions about the
  outcome.

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Heat and Density

• Energy
• Land takes less calories needed to heat per
  unit.

• Energy
• Water takes more calories to heat per unit.

• Albedo
• Water heats more slowly

• Albedo
• Land heats faster than water.

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Heat and Density

• Heat Retention
• Land loses heat faster than water

• Heat Retention
• Water retains heat longer than land.

• Surface Reflectivity
• Sand absorbs heat energy more quickly (5 15)

• Surface Reflectivity
• Water reflects more at low angles and absorb more
  when heat is directly overhead

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Heat and Density

• Lustre
• Land is opaque.

• Lustre
• Water is transparent.

• Heat Mixing
• Land allows no heat mixing.

• Heat Mixing
• Water allows mixing by currents.

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Heat and Density

• Evaporation
• Land loses less water vapor to the air than
  standing water.

• Evaporation
• Water loses more water vapor than land.

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HEAT AND DENSITY