Models and Dimensions of Earth

I. Model=

A. Types and Examples of Models:

1. __________________ - provides us with information through our sense of sight.

PHYSICAL

Geographical Globe

Simplified representation of an object or idea

Models and Dimensions of Earth

2. __________________ - a physical model with moving parts so that it can perform the functions or movements as the original model.

Mechanical

Model Electric trains

Models and Dimensions of Earth

3. __________________ - mathematical relationships expressed by symbols, formulas, and equations.

Mathematical model

Equations

Models and Dimensions of Earth

4. __________________ - a graph to provide a “picture” of a relationship of symbols, formulas, and equations.

Graphic model

Temperature vs. Month Graph

Models and Dimensions of Earth

5. __________________ - models that can only exist in someone’s mind.

Mental

Water is made of 2 Hydrogen and 1 Oxygen molecules

II. Shape of Earth

A.________________ - _________________

1. ______________________

2. ______________________

3. Diagram of an __________________________

Equatorial Diameter

NOT TO

SCALEPolar diameter

Oblate spheroid Flattened sphere

Flattened at the poles

Bulging at the equator

Oblate spheroid

4. Earth’s equatorial circumference is ______________

than its polar circumference.

a. Equatorial circumference - ___________________

b. Polar circumference - ______________________

greater

24,900 miles

24,860 miles

B. Causes of Earth’s Shape

1. _____________________ an inward pulling force. This force pulls equally in all directions and causes earth to be _______________________.

Key___________= force of gravity

.

Gravity

an oblate sphere

2. ________________- an apparent outward force caused by the spinning (or rotating) of earth on its axis. This force causes earth to _________________.

a. The faster the rotational speed, the ____________ the centrifugal force.

b. (1) How long does it take each location to make one complete rotation?

X___________

Y___________

Centrifugal Force

fasterRotate

24 hours

24 hours

X Y

(2) Which location, X or Y, travels a greater distance to make one complete rotation? ____________

(3) At which location, X or Y, is the rotational speed greater? _____________

(4) At which location, X or Y, is centrifugal force greater? _____________

c. Therefore, the greater centrifugal force causes earth to bulge at the __________________________.

Location X

Location X

Location X

Equator

X Y

C. Evidence of Earth’s Shape

1. Photographs from space reveal that Earth is

_______________________

2. Observations of ships on the horizon

The gradual “appearance” or “disappearance” of a ship over the horizon is evidence that earth’s surface is ____________________.

Round

Curved

3. Observations of an Eclipse of the Moon (as viewed from Earth)

a. As viewed from space:

As the moon orbits Earth, and travels from position 1 to position 2, it passes through ______________________________________.Earth’s shadow

b. As viewed from Earth:

c. Earth’s shadow on the moon (full moon) during a lunar eclipse provides evidence that Earth is __________________________. Curved

4. Measurement of Gravity

a.

b. The shorter the distance between two objects, the greater the gravitational force. Therefore a person or object that is closer to the center of Earth (the center of gravity) would weight more than when the person or object is farther from the center of gravity.

c. (1) If Earth is an “oblate spheroid”, where on the surface of Earth would a person be closer to the center of Earth?

_________________________

(2) Where on the surface of Earth would a person weigh the most?

_________________________

d. Under what circumstance would a person weigh the same everywhere on Earth?

At the poles

At the poles

If Earth was a perfect sphere.

5. Observation of North Star, Polaris

a. The altitude of Polaris changes as an observer moves north or south (in the Northern Hemisphere);

this is because Earth is _____________, and its surface is _____________________.

(Altitude is the height, measured in degrees that a heavenly body is above the horizon of the observer).

a spherecurved

Observer LATITUDE ALTITUDE of POLARIS

1

2

3

4

90 ° North 90 °

60 ° North 60 °

30 ° North 30 °

0 ° 0 °

c.

North Pole 90 ° N

Altitude of Polaris = 90 °

90

Canada 60 ° N

Alt. of Polaris 60 °

60

Atlanta 30 ° N

Alt. of Polaris 30 °

30 0

Equator 0°

Alt. of Polaris 0°

d. Summary:

e. Locating the North Star

As latitude increases altitude of Polaris increases.

NORTH STAR- POLARIS

Altitude of Polaris = Latitude

IV. Latitude and Longitude

A.Latitude-

1. Parallels-

2. Equator-

3. North/South Pole-

4.

The angular distance North or South of the equator.

Lines that measure latitude that never touch.

Reference line for 0° latitude. Midway between both poles.

Highest possible latitude, 90° North, 90° South

90°North

90°South

0° Equator

30°North Tropic of Cancer

60° North Arctic Circle

30°South Tropic of Capricorn

60° South Antarctic Circle

IV. Latitude and Longitude

B. Longitude-

• Meridians-

• Prime Meridian-

• International Date Line-

The angular distance East or West of the Prime Meridian.

Lines of longitude that connect from pole to pole.

Reference line for longitude 0°, that goes through Greenwich England.

Largest possible longitude, 180°

Location Latitude Longitude

1

2

3

4

5

30 ° North 120 ° West

45 ° South 75 ° East

0 ° 135 ° West

45 ° North 135 ° East

70 ° South 165 ° West

Location Latitude Longitude

6

7

8

9

10

45 ° South 180°

45 ° North 75 ° West70 ° North 0 °

15 ° South 15 ° East

20 ° South 45 ° West

CONTINENTS

A

B

C

D

E

F

G

North AmericaSouth AmericaEurope

Asia

AfricaAustraliaAntarctica

Oceans

H

I

J

K

L

Atlantic

PacificIndian

AntarcticArctic

D. Earth’s Time Zones

1. As Earth rotates on its axis, half of earth is facing the sun and is experiencing daylight; the other half is in darkness and is experiencing night.

2. When the sun is directly over a certain meridian, it is 12 noon at any location at or near that meridian.

12 Noon

12 AM

6 AM

6 PM

3. Think:

Earth is a sphere/degrees in a circle =

Time/ Hours to make one complete rotation =

4. a. Number of time zones on Earth =

b. Approximate width of each time zone =

Rate of Earth’s rotation ?

360° =

24 hours

15°/hr

24 time zones

15°

5. a. If it is Wednesday, and you cross the International Date Line going west, it would then be _________________

b. It is Tuesday, and you cross the International Date Line while traveling east, it would then be _________________

Tuesday

Wednesday

6.

a. How many time zones are there in the continental U.S.?

_________________

b. Is it earlier or later in California than New York?

_________________

c. If it is 8:00 EST, what time is it in PST?

_________________

d. It is 6:00 MST, what time is it in EST?

____________________

4 time zones

Earlier

5:00

8:00