Notes Shape of Earth.notebook

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November 05, 2015

Oct 291:41 PM Oct 291:41 PM

Causes of the Earth’s Shape

•   Gravity:  Pushing _____________ equally in all directionsinward

Oct 291:41 PM

Causes of the Earth’s Shape

•   Centrifugal Force:  ________________ acting force caused

by the __________________ of Earth on its axis.

Outwardspinning

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Causes of the Earth’s Shape

  • Actually causes Earth to ___________________

•   The ________________ the speed, the

      ________________ the _________________ force

expand

greatergreater expanding

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Causes of the Earth’s Shape

Does the Earth rotate at the same rate of speed at every location ?

Oct 291:41 PM

Causes of the Earth’s Shape

• Therefore, the __________________ expanding force

       is at the __________________

•   This causes the Earth to ______________ slightly at

   the __________________ and _________________

   at the ___________________

greater

equator

bulge

equator

flattenpoles

Notes Shape of Earth.notebook

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November 05, 2015

Oct 291:41 PM

Causes of the Earth’s Shape

• Because of this, the shape of the Earth is called an

       ____________________________________________

Your drawing here:

OBLATE SPHEROID( a flattened sphere)

Oct 292:19 PM

Oct 292:23 PM

Equatorial Diameter > Polar Diameter

http://www.mathsisfun.com/equallessgreater.html

(about 40 km greater)Please add to your notes:

Oct 291:41 PM

Observable Evidence of Earth’s Curved Surface

1.  _______________ Eclipse

•   Shows a ________________ shadow on the _________      as it enters and exits Earth’s shadow

http://www.youtube.com/watch?v=L1qCcgp8Sg4&feature=related

http://www.youtube.com/watch?v=2dSdRJ7dXjo&feature=related

Lunar

curved moon

Oct 291:41 PM

Observable Evidence of Earth’s Curved Surface

2.  Ships ___________________ over the __________________

      in __________ directions

disappear horizon

all

Oct 291:41 PM

Observable Evidence of Earth’s Curved Surface

3.  ______________________ from spacePictures

http://www.mathsisfun.com/equal-less-greater.htmlhttp://www.youtube.com/watch?v=L1qCcgp8Sg4&feature=relatedhttp://www.youtube.com/watch?v=2dSdRJ7dXjo&feature=related

Notes Shape of Earth.notebook

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November 05, 2015

Oct 291:41 PM

Okay … it‛s round, but how round (how big)?

Oct 291:41 PM

Determining Earth’s Circumference

•   Eratosthenes’ Method

•   Ancient Greek mathematician (~200 BC) 

http://www.wimp.com/greekscientist/

Oct 291:41 PM

Determining Earth’s Circumference

•   Eratosthenes’ Method

•   Well at Syene had _____ shadow at noon on a given       day of the year.

•   A stick in the ground at Alexandria cast a shadow with

      an angle of _____ degrees at that ________ same time.

•   Knew the ___________ between both locations.

no

7.2 exactdistance

Oct 291:41 PM

In order for Eratosthenes to do his math, he needed know:

1. The date and time the sun would be directly above one of the two locations.

2. The distance between the two locations.

3. The angle formed between the two locations from the center of the Earth.

Add these notes on a separate piece of paper and keep them with this note-taking guide.

Oct 291:41 PM

In order for Eratosthenes to due his math, he needed know:

1. The date and time the sun would be directly above one of the two locations.

Summer Solstice (longest day of the year) on June 21st....sun directly above Syene (@ 23.50 North Latitude)

Don't mark your drawing until later.....

Oct 291:41 PM

In order for Eratosthenes to due his math, he needed know:

2. The distance between the two locations.

Camel caravans travelled100 stadia per dayand it took 50 daysto make the journey.

5000 stadia(500 miles)

http://www.wimp.com/greekscientist/

Notes Shape of Earth.notebook

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November 05, 2015

Oct 291:41 PM

In order for Eratosthenes to due his math, he needed know:

3. The angle formed between the two locations from the center of the Earth.

This could be observed (and measured) at noon on June 21st.

7.20

Oct 291:41 PM

In order for Eratosthenes to due his math, he needed know:

3. The angle formed between the two locations from the center of the Earth.

According to the rule of alternateinterior angles

7.20

7.20

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7.20

7.20

500 miles

Place this information on the diagram in your note-taking guide:

Oct 291:41 PM

Determining Earth’s Circumference

•   Eratosthenes’ Method

•  Used rule of alternate interior angles along with     Part/Whole proportion to make his calculation

Oct 291:41 PM

Determining Earth’s Circumference

•   Eratosthenes’ Method

•  Used rule of alternate interior angles along with     Part/Whole proportion to make his calculation

Part = 7.2 0 = 500 milesWhole 3600 C

Oct 291:41 PM

Determining Earth’s Circumference

•   Eratosthenes’ Method

•  Used rule of alternate interior angles along with     Part/Whole proportion to make his calculation

7.2 0 = 500 miles 3600 C

cross multiply

7.20 (C) = 3600 (500 miles)

Notes Shape of Earth.notebook

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November 05, 2015

Oct 291:41 PM

Determining Earth’s Circumference

•   Eratosthenes’ Method

•  Used rule of alternate interior angles along with     Part/Whole proportion to make his calculation

7.20 (C) = 3600 (500 miles)

7.20 7.20

Oct 291:41 PM

Determining Earth’s Circumference

•   Eratosthenes’ Method

•  Used rule of alternate interior angles along with     Part/Whole proportion to make his calculation

7.20 (C) = 3600 (500 miles)7.20 7.20

C = 360 (500 miles) = 180,000 miles7.2 7.2

Oct 291:41 PM

Determining Earth’s Circumference

•   Eratosthenes’ Method

•  Used rule of alternate interior angles along with     Part/Whole proportion to make his calculation

C = 360 (500 miles) = 180,000 miles7.2 7.2

C = 25,000 miles

Oct 291:41 PM

Determining Earth’s Circumference

•   Eratosthenes’ Method

•  Used rule of alternate interior angles along with     Part/Whole proportion to make his calculation

C = 360 (500 miles) = 180,000 miles7.2 7.2

C = 25,000 milesActual circumference = ~24,900 miles !

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