Physics Its All Around Us

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Physics!Its All Around Us!

• A Science club sponsored by the UNL SEPPO program
  and the LPS CLC program

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What is SEPPO?

• Stands for Science Education Partnerships in
  Public Outreach
• What does SEPPO do ?
• Presentations at
• Schools, Libraries,
• Observatories, Museums,
• 4-H events,

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Tentative Outline

• Week 1 How Much Stuff
• Mass, Weight, Density
• Week 2 Staying Balanced
• Week 3 Im Under Pressure
• Week 4 Round Round
• Week 5 Wave at Me!
• Week 6 Makin Music
• Week 7 Im Charged
• Week 8 Magnetic Attraction

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Lets get Acquainted!

• SEPPO presenters introduce themselves
• Students introduce themselves

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How Much Stuff (Mass, Weight Density)

• Science Club Week 1

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Big Questions to think About
?

• What are you made of ?
• How much of you is there ?
• How can we describe how much of you there is

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Mass

• is a measure of how much matter there is in
  something -- usually measured in grams or
  kilograms in science
• causes an object to have weight in a
  gravitational field
• describes how difficult it is to get an object
  moving

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How Can We Determine Mass ?
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Activity

• Your group should measure the mass of each of the
  3 unknown masses (rocks)
• Measure each mass with
• the triple-beam balance
• the balancing scale
• a spring scale
• and record its value on your data sheet
• Who can get done first?

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Big Questions
?

• If you took a 1 kg mass to the moon, would its
  mass still be 1 kg ?
• If you took a 70 pound kid to the moon, would he
  still weigh 70 pounds?

Yes, because mass is a measure of how much
matter is present and is the same everywhere.
No, because weight is a measure of how much one
body is pulling on another and the force of
gravity on the moon is less than that on the Earth
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Mass Inertia an objects resistance to motion
Would it be more difficult to pull an elephant or
a mouse?
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Pulling Out a Table Cloth
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Mass Weight

• In the metric system
• The kilogram is used to measure mass
• The Newton is used to describe weight\
• In the American system
• The slug is used to describe mass
• The pound is used to describe weight

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The Standard Kilogram
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What is density?

• A measure of how much mass is in a certain volume
  of space
• The density of a substance is equal to its mass
  divided by its volume

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How would you measure the density of an object?
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Activity

• Each group has 8 objects 4 each have two
  different values of densities
• With the help of your SEPPO worker you should
• measure the mass of the of each object
• measure the height and determine the volume of
  each mass
• graph your data
• determine the densities of the substances

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Which has greater density?A) a basketballB) a
bowling ball
?
Remember that density is equal to mass divided by
volume. Since both of these balls have pretty
much the same volume, the bowling ball must have
the large density since it has the larger mass.

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Densities
1000 kg/m3 is equal to 1 g/cm3 Thus, either
value could be used to describe the density of
water.
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Making Salad Dressing
Oil floats on water because of its higher density!
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Does a Can of Pop Float?
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I. Lake Nyos in Cameroon
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Details on the Lake Nyos Disaster

• On 26 August 1986 an enormous volume of carbon
  dioxide (CO2) was released from Lake Nyos that
  killed about 1700 people. Two years earlier in
  Lake Monoun there was a smaller release of CO2
  that killed 37 people.
• CO2 is released through volcanic processes and
  dissolves in the lake. Mechanism triggering the
  release is unknown
• Due to its higher density of 1.98 kg/m3 compared
  to 1.29 kg/m3 for air, CO2 hugs the ground and
  asphyxiates people and animals at concentrations
  above 10.

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Degassing Lake Nyos

• Autosiphon project
• The Nyos Organ project, as it is known, involves
  inserting 12 pipes into the lake.
• The pipe shown here was inserted 210 meters into
  Lake Nyos. The pipe spews 90 carbon dioxide and
  10 water to a height of 50 meters
• By doing so, the accumulated carbon dioxide in
  the depths of the lake will be gradually released
  at very high altitude in the atmosphere and will
  not be dangerous to people living nearby

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II. The Dead Sea

• Israels Dead Sea is 400 ft below sea level. The
  desert sun evaporates much of the water and
  leaves behind many mineral salts. (It is ten
  times saltier than the ocean.) Thus, it has a
  density of 1200 kg/m3

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Floating in the Dead Sea
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III. Icebergs
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• The density of fresh water is 1000 kg/m3 while
  the density of salt water is 1030 kg/m3. Thus,
  an iceberg floats but just barely.
• Thus, icebergs are particularly dangerous to
  ships since most of the iceberg is below the
  water line.