physical geodesy

Question 1

the study of the physical properties of the gravity field of the Earth,
the geopotential, with a view to their application in geodesy.

Answer 1

Physical Geodesy

Question 2

first to formulate the fact that
two bodies attract each other.

Answer 2

Sir Isaac Newton (1687)

Question 3

two bodies attract each other.

Answer 3

Gravitational Force

Question 4

• The sum of gravitational force and the centrifugal reaction acting on a
  body
• Since the gravitational force is much stronger than the centrifugal
  reaction, gravity causes an object to have weight.

Answer 4

Gravity

Question 5

1 gal = ?

Answer 5

1 cm/sec2

Question 6

1000 gals = ?

Answer 6

1 kgal = 1 kilogal

Question 7

0.001 gals = ?

Answer 7

1 mgal = 1 milligal

Question 8

0.000001 gals = ?

Answer 8

1 μgal = 1 microga

Question 9

the angular velocity of a point is dependent on the latitude of the point since the distance P from the spin axis
changes.

Answer 9

Centrifugal Force

Question 10

Phenomenon of light, radio waves, etc. being deflected in passing obliquely from one medium to another of varying density.

Answer 10

Refraction

Question 11

The force which pulls down a body towards the center of the earth. The sum of gravitational force and the centrifugal reaction acting on a body. It causes an object to have weight.

Answer 11

Gravity

Question 12

Magnitude of g at the poles

Answer 12

983.221 gals

Question 13

Magnitude of g at the equator

Answer 13

978.049 gals

Question 14

it can be seen that gravity varies in
relation to both _______ and _______ of the point

Answer 14

height and latitude

Question 15

The first gravity measurement was made using a pendulum in a clock.
In 1672, _____, a French astronomer, noted that a clock that kept perfect time in Paris lost 2.5 minutes a day at the equator. In fact, a shorter pendulum was required at the equator to keep the correct
time.

Answer 15

Richer

Question 16

_______ developed the theory of pendulum behavior. The
period, T or P, of the oscillation of the pendulum is directly related to
the gravitational acceleration, g.

Answer 16

Huygens

Question 17

Only one parameter is observed. The other one is kept constant.

Answer 17

Relative Determination

Question 18

P is measured at two station, and the ratio of these corresponding
values of g are determined.

Answer 18

Relative Determination of Gravity

Question 19

A compensation factor used in gravitational surveys that takes into
account the decrease in the force of gravity with increasing altitude, assuming only air intervenes between the observer and sea level.

Answer 19

Free-air Correction

Question 20

Free-air Correction

Answer 20

g ground-level > g high up

Question 21

Variations in Gravity due to Height
gravity correction:

Answer 21

Cr =-0.3086H (mgal)(if m)

Question 22

• Computation of positions are taken with respect to an ellipsoid
• Measurements are made on the apparent topographic surface of the earth
• One other surface measurement is involved in geodetic
  measurements

Answer 22

Geoid

Question 23

mathematically defined regular surface with specific
dimensions.

Answer 23

ellipsoid

Question 24

coincides with that surface to which
oceans would conform over the entire earth if free to adjust to the
combined effect of the earth’s mass attraction and the centrifugal
force of the earth’s rotation

Answer 24

Geoid

Question 25

the shape of an imaginary global ocean dictated by
gravity in the absence of /des and currents.

Answer 25

Geoid

Question 26

As a result of uneven distribution of the earth’s mass, the geoidal surface is irregular and, since the ellipsoid is a regular surface, the two will not coincide.

Question 27

3 Geoid Separation

Answer 27

1. Geoid Undulations
2. Geoid Heights
3. Geoid Separations

Question 28

Geoid is a surface along which the gravity potential is ______ equal and to which the direction of gravity is always
________.

Answer 28

everywhere - perpendicular

Question 29

Tidal Datums are observed for
how many years?

Answer 29

19 years - Metonic Cycle

Question 30

measured from the geoid to the point along the
plumb line

Answer 30

Orthometric Height (H)

Question 31

measured from the ellipsoid to the point along the normal

Answer 31

Ellipsoidal Height (h)

Question 32

Difference in elevation between the ellipsoid to the geoid. Measured from ELLIPSOID

Answer 32

Geoid Height/ Separation/ Undulation (N)

Question 33

Geoid below the ellipsoid

Answer 33

NEGATIVE VALUE

Question 34

Geoid above the ellipsoid

Answer 34

POSITIVE VALUE

Question 35

the difference between the observed
acceleration of free fall, or gravity, on a planet’s surface, and the
corresponding value predicted from a model of the planet’s gravity
field

Answer 35

Gravity Anomaly

Question 36

The angle between the plumb line which is perpendicular to the geoid (vertical) and the and the perpendicular to the ellipsoid (normal)

Answer 36

Deflection of the Vertical