Name ___________________________________
Date _______________
Class Period _____
Instructor _____________
Lab Period ______
5 points
Earth’s Shape
DATA SHEET
DATA TABLE: Please fill out the table as completely as possible.
ROUNDNESS: 39 points
Object
Equatorial
Diameter
Polar
Diameter
Roundness
5 points
Earth
12,756 km
12,714 km
5 points
5 points
5 points
5 points
5 points
5 points
Blue Globe
White Globe
And the roundest is: _____________________________
4 points
SMOOTHNESS: 29 points
Measured Relief Globe Height of Mt. Everest:___________________
5 points
Calculated Relief Globe Height of Mt. Everest:___________________
10 points
Percent Deviation of Height of Mt. Everest:______________________
10 points
And the smoothest is: _____________________________
4 points
QUESTIONS:
Answer questions # 1 – 5 in complete sentences. Answers should not
contain any personal pronouns (they, I, them, we, etc.)
3 POINTS EACH
1.
2.
3.
4.
5.
6.
A
B
C
D
7.
A
B
C
D
8.
A
B
C
D
9.
A
B
C
D
Lab #3 Earth’s Shape
INTRODUCTION: Please read this as it contains information required to perform the
lab and material that may be tested.
Pictures of earth taken from space show that the earth appears to be perfectly round and
smooth. However, to us, the earth appears to have a highly irregular surface. In addition,
accurate measurements of the earth's shape show that the equatorial diameter is slightly
different from the polar diameter. This forms a shape known as an oblate spheroid.
LABORATORY PROCEDURES: Please follow these directions and any directions
provided by the instructor. Follow laboratory safety rules at all times.
A. ROUNDNESS
The ratio of the polar diameter to the equatorial diameter of a sphere is a measure of its
roundness. Dividing the equatorial diameter by the polar diameter would give a value of one
since both diameters are equal in a perfect sphere. The farther from 1 the actual computed
ratio is, the less spherical a globe is.
Use the values given for the equatorial and polar diameters of the earth in the data table to
calculate the roundness of the earth. Divide the polar diameter into the equatorial diameter.
The larger number goes on top, inside, or into the calculator first. Record this value on the
data table.
Measure the polar and equatorial diameter of the small, plastic, blue globe. Record these
measurements on the data table. Divide the smaller number into the larger number. That
means the larger number goes on top, inside, or into the calculator first.
Measure the polar and equatorial diameter of the larger, white, plastic globe. Record these
measurements on the data table. Divide the smaller number into the larger number. That
means the larger number goes on top, inside, or into the calculator first.
B. SMOOTHNESS:
A relief globe shows the relative height (relief) of its surface features, such as mountains. It
is a scale model of the earth. The following procedure will help you determine whether or
not these features are constructed to scale. To do this you must use a proportion. Proportions
are usually set up like the one below.
Little part of Object A
---------------------------Big part of Object A
=
Little part of Object B
---------------------------Big part of Object B
Measured Relief Globe Height of Mt. Everest: With a ruler, measure the height of Mt.
Everest to the nearest tenth of a centimeter on the white, plastic relief globe. Record this
number on the data table.
Actual Height of Mt. Everest: 8.8 km.
Average Earth Diameter:
12740 km
Relief Globe Diameter: Measure the equatorial diameter of the diagram of the relief globe.
Calculated Relief Globe Height of Mt. Everest: Using these values and the proportion
shown below, solve the relief globe height of Mt. Everest to correct scale for this diagram of
a globe.
Actual Height
of Mt. Everest (km.)
------------------------=
Average
Earth Diameter (km.)
Calculated
Relief Globe Height
of Mt. Everest (cm.)
unknown X
--------------------------Relief Globe
Diameter (cm.)
Cross multiply and solve for X by dividing.
Percent Deviation of Mt. Everest: Determine the percent deviation between the height of
Mt. Everest on the globe and the height it should have been if drawn to the correct scale. The
equation for percent deviation from accepted value is in the Reference Tables.
QUESTIONS: ANSWER QUESTIONS #1 – 5 IN COMPLETE SENTENCES!
Answers should not contain any personal pronouns (they, I, them, we, etc.)
3 POINTS EACH
1.
What is the name for the true shape of the earth? You may have to read the
introduction to come up with this one.
2.
What is rounder, the earth or an average classroom globe? Use data from this lab to
support your answers.
3.
What is smoother, the earth or an average classroom globe? Use data from this lab to
support your answers.
4.
If the earth were shrunk down proportionately, what would it most resemble, an
orange, a pear a billiard (pool) ball, an egg or a Fender Stratocaster with a whammy
bar? Why?
5.
How do we (humans) know that the earth is somewhat spherical? List at least two
ways.
6.
Based on the diagram below, what is the circumference of planet X?
A)
B)
C)
D)
7.
18,000 km
9,000 km
24,000 km
36,000 km
To an observer on the moon, the Earth in full phase would appear to be shaped like
A) a pear
B) a basketball
C) a football
D) an egg
8.
According to the data table below, what is the exact shape of the earth?
Actual Dimensions of the Earth
Equatorial Radius
Polar Radius
Equatorial Circumference
Polar Circumference
A)
B)
C)
D)
9.
6,378 km
6,357 km
40,076 km
40,008 km
slightly flattened at both the Equator and the Poles
slightly flattened at the Equator and slightly bulging at the Poles
slightly bulging at the both the Equator and the Poles
slightly bulging at the Equator and slightly flattened at the Poles
The true shape of the Earth is best described as a
A) perfect sphere
B) slightly oblate spheroid
C) very oblate spheroid
D) highly eccentric spheroid