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NAV SEL FOR EXAM DEC2020 THEORY-LX-MODULE1
1.
In which statement is the "Mean Sun" best described?
a) The mean sun is a fictitious sun the orbit of which coincides with that of the apparent sun, but is corrected for mean astronomical and atmospheric refraction.
b) The mean sun is a fictitious sun coinciding each year with the apparent sun at the Spring Equinox and travelling along the ecliptic at uniform speed.
c) The mean sun is a fictitious sun the orbit of which coincides with that of the apparent sun, but is corrected for the mean difference in hour angle.
d) The mean sun is a fictitious sun coinciding each year with the apparent sun at the Spring Equinox and travelling along the celestial equator at uniform speed.
2.
What is the meaning of the term "standard time" ?
a) It is the time zone system applicable only in the USA
b) It is another term for UTC
c) It is an expression for local mean time
d) It is the time set by the legal authorities for a country or part of a country
3.
The time interval between sunrise and sunset is dependent on?
a) The declination of the sun and the latitude of the observer.
b) The inclination of the axis of the earth and the longitude of the observer.
c) The latitude and the longitude of the observer.
d) The date and the longitude of the observer.
4.
The local hour angle of the mean sun at 1200 LMT is?
a) 090 degrees.
b) 180 degrees.
c) 000 degrees.
d) 270 degrees.
5.
Which definition describes best the notion "Poles"?
a) The Poles are the points of intersection between the surface of the earth and the extended line joining the star Polaris with the centre of the Earth.
b) The Poles are the points on the surface of the earth which have the same distance to all points on the ecliptic.
c) The Poles are the points of intersection between the earths axis and the surface of the earth.
d) The Poles are the points on the surface of the earth where gravity acts under an angle of exactly 90 degrees.
6.
The reason that the solar day lasts longer than the sidereal day is that?
a) The sun has its own movement through the universe opposite to the movement of the earth due to the gravitational forces of the celestial bodies.
b) Both the direction of rotation of the earth around its axis and its orbital rotation around the sun are the same.
c) The orbital speed of the earth around its axis diminishes slowly.
d) The orbital track of the earth around the sun is an ellipse.
7.
Kepler's second law states that?
a) The radius vector sun-earth sweeps out equal areas in equal time.
b) The length of the radius vector sun-earth is directly proportional to the square root of its angular speed.
c) The radius vector sun-earth moves at constant angular speed.
d) The area swept out by the radius vector sun-earth per hour increases with increasing length of the radius vector.
8.
Which statement about the orbit of the earth is correct?
a) The orbit of the earth around the sun is a circle with the sun at a point next to its centre.
b) The orbit of the earth around the sun is an ellipse with the sun mid-way between the two foci.
c) The orbit of the earth around the sun is an ellipse with the sun at one of the foci.
d) The orbit of the earth around the sun is a circle with the sun at its centre.
9.
The Earth can be considered as being a magnet with the:
a) red pole near the north pole of the earth and the direction of the magnetic force pointing straight down to the earth's surface
b) blue pole near the north pole of the earth and the direction of the magnetic force pointing straight down to the earth's surface
c) red pole near the north pole of the earth and the direction of the magnetic force pointing straight up from the earth's surface
d) blue pole near the north pole of the earth and the direction of the magnetic force pointing straight up from the earth's surface
10.
At (54 N 020 W) the sun rises on November 28th at 09:01 UTC. At (44N 020W) the sun will rise?
a) Also about 09:01 since both positions are situated on the same meridian.
b) Later since the latter position lies further south.
c) Earlier since the latter position lies further south.
d) At 07:41 LMT.
11.
The length of the apparent solar day varies continuously throughout the year. This is caused by?
a) The fact that the earth is closest to the sun around the 1st of January.
b) The equation of time.
c) The fact that the earth is closest to the sun around the 1st of July.
d) The tilt of the earth's axis and the elliptical orbit of the earth around the sun.
12.
Consider the positions (00N/S, 000E/W) and (00N/S, 180E/W) on the ellipsoid. Which statement about the distances between these positions is correct?
a) The route via the equator is shorter than the route via the South Pole.
b) The route via the North Pole is shorter than the route along the equator.
c) The route via either pole and the route via the equator are of equal length.
d) The route via the South Pole is shorter than the route via the North Pole.
13.
Two places are situated on the same parallel in the southern hemisphere. The great circle, rhumb line and straight line between these places are drawn on a polar stereographic projection. Which statement is correct?
a) The correct sequence from north to south is great circle, straight line, rhumb line.
b) The great circle is situated between the parallel and the straight line, because the concave side of the great circle is always pointed towards the pole.
c) The rhumb line is situated between the parallel and the straight line, because the shortest distance between two places on the earth is always a great circle.
d) The great circle is situated between the parallel and the straight line, because the concave side of the great circle is always pointed towards the equator.
14.
An Agonic line is a line that connects:
a) positions that have 0° variation
b) positions that have the same variation
c) points of equal magnetic dip
d) points of equal magnetic horizontal field strength
15.
When proceeding, on a given date, along a parallel towards the East, the moment of sunrise will occur one hour earlier every 15 degrees difference in longitude when it is expressed in?
a) LMT.
b) UTC.
c) Standard time.
d) LAT (local apparent time).
16.
Standard time for some areas is listed in the Air Almanac as UTC+13 instead of UTC-11. The reason for this is?
a) The sense of the earth rotation.
b) Keeping the same date as the political and or economical entity to which they belong.
c) The setup of the sunrise/sunset tables.
d) The fact that they are keeping daylight saving time.
17.
Location A is at 50N 030W and location B is at 50S 030W. ON the 27th November it is noted that:
a) Sunrise and sunset will be at the same time at A and B.
b) Sunrise will be later at A than at B and sunset will be earlier at A than at B.
c) Sunrise will be earlier at A than at B and sunset will be earlier at A than at B.
d) Sunrise will be later at A than at B and sunset will be later at A than at B.
18.
The reason that the solar day last longer than the sidereal day is that?
a) The orbital speed of the earth around its axis diminishes slowly.
b) Both the direction of rotation of the earth around its axis and its orbital rotation around the sun are the same.
c) The orbital track of the earth around the sun is an ellipse.
d) The sun has its own movement through the universe opposite to the movement of the earth due to the gravitational forces of the celestial bodies.
19.
Which statement is correct?
a) The planets move around the sun like all the stars of the solar system.
b) The sun moves in an elliptical orbit around the earth.
c) The Solar system consists of the sun, planets and stars.
d) The earth is one of the planets which are all moving in elliptical orbits around the sun.
20.
The first law of Kepler states?
a) The angular speed of the planets in the orbit around the sun is constant.
b) Planets move in elliptic orbits with the sun at one of the foci.
c) Planets move around the sun in a circular path.
d) All planets orbit around the sun at the same speed.
21.
On an oblate spheroid representing the earth's shape:
a) 1 Minute of arc along the meridian at 0 N/S measures the same distance as 1 minute of arc at 90 N/S.
b) 1 minute of arc along the equator measures a greater distance than 1 minute of arc along the meridian at latitude 45N/S.
c) 1 minute of arc along the meridian at low latitudes measures a greater distance than 1 minute of arc along the meridian at high latitudes.
d) 1 minute of arc along the equator measures the same distance as 1 minute of arc along the meridian at latitude 45N/S.
22.
Which statement regarding the apparent sun and the mean sun is correct?
a) The mean sun moves along the ecliptic, the apparent sun along the celestial equator.
b) The apparent sun is the visible sun, the mean sun is a fictitious sun.
c) The apparent sun is not important for navigation as differences in time with the mean sun is normally 4 seconds.
d) The apparent sun is a fictitious sun coupled to UTC, the mean sun is related to the local mean time.
23.
Which of the following alternatives is correct when you cross the international date line?
a) The date will always be the same.
b) If you are crossing from westerly longitude to easterly longitude the date will remain the same.
c) The date will increase when going on a easterly heading.
d) The date will increase when going on a westerly heading.
24.
When crossing the International Date Line, which of the following statements can be considered correct?
a) When crossing from west to east longitude then date will stay the same.
b) The date will increase when going on a easterly heading.
c) There will be no change in date.
d) The date will increase when going on a westerly heading.
25.
The time difference in Local Mean Time between sunset at positions A(50N 120E) and B(50S 120E) on the 21st of November is?
a) Negligibly small because A and B are located symmetrically to the equator.
b) Some hours and the sun rises earlier in B than in A.
c) Negligibly small because A and B are located on the same meridian.
d) Some hours and the sun rises earlier in A than in B.
26.
At 0000 Local Mean Time of an observer?
a) The mean sun is in transit with the observer's meridian.
b) The apparent sun is in transit with the observer's meridian.
c) The apparent sun is in transit with the observer's anti-meridian.
d) The mean sun is in transit with the observer's anti-meridian.
27.
Which statement about meridians is correct?
a) A meridian forms a complete great circle.
b) The plane of a meridian is parallel to the equator.
c) All meridians are parallel with the meridian at Greenwich.
d) A meridian and its anti-meridian form a complete great circle.
28.
The direction of True North for any observer is?
a) The direction of the observer's meridian to the North Pole.
b) The direction of the Greenwich meridian to the North Pole.
c) The reading of the observer's compass corrected for deviation and local variation.
d) The direction of the observer's magnetic north corrected fro local variation.
29.
What is the correct definition of latitude of a position on the earth?
a) Latitude is the angle between the plane of the Prime Meridian and the plane of the meridian of the position.
b) Latitude is the angle between the earth's rotational axis and the line from the centre of the earth to the position.
c) Latitude is the angle between the plane of the ecliptic and the parallel of the position.
d) Latitude is the angle between the plane of the equator and the line from the centre of the earth to the position.
30.
In order to fly from position A (10°00'N, 030°00'W) to position B (30°00'N, 050°00'W), maintaining a constant true course, it is necessary to fly:
a) a straight line plotted on a Lambert chart
b) a rhumb line track
c) the constant average drift route
d) the great-circle route
31.
Complete the following statement regarding magnetic variation. . The charted values of magnetic variation on earth normally change annually due to?
a) magnetic pole movement causing numerical values at all locations to increase.
b) a reducing field strength causing numerical values at all locations to decrease.
c) an increasing field strength causing numerical values at all locations to increase.
d) magnetic pole movement causing numerical values at all locations to increase or decrease
32.
Which statement is true?
a) Only the declination of the sun will affect the duration of civil twilight.
b) The duration of civil twilight on 21st of March and on 23rf of September is equal at al places on Earth independent of latitude.
c) The declination of the sun and the latitude of the observer will affect the duration of civil twilight.
d) Civil twilight at the equator lasts longer than at 60N or 60S because the radius of the equator is larger than the radius of the 60 degree parallels.
33.
How does the convergence of any two meridians on the Earth change with varying latitude?
a) It changes with the sine of latitude.
b) It is of constant value and does not change with latitude.
c) It decreases with decrease of latitude.
d) It changes with cosine of latitude.
34.
Isogrives are lines that connect positions that have:
a) O° magnetic dip
b) the same variation
c) the same horizontal magnetic field strength
d) the same grivation
35.
Isogonals converge at the:
a) North and South geographic and magnetic poles
b) Magnetic equator
c) North magnetic pole only
d) North and South magnetic poles only
36.
A negative (westerly) magnetic variation signifies that :
a) True North is West of Magnetic North
b) Compass North is East of Magnetic North
c) Compass North is West of Magnetic North
d) True North is East of Magnetic North
37.
The value of magnetic variation:
a) cannot exceed 90°
b) varies between a maximum of 45° East and 45° West
c) has a maximum of 180°
d) must be 0° at the magnetic equator
38.
Which statement is true?
a) The duration of civil twilight on the 21dt of March and on the23rd of September is equal at all places on the earth, independent of latitude.
b) Civil twilight at the equator last longer than at 60N or 60S because the radius of the equator is larger than the radius of the 60 degree parallels.
c) Only the declination of the sun will affect the duration of civil twilight.
d) The declination of the sun and the latitude of the observer will affect the duration of civil twilight.
39.
The maximum difference in distance when proceeding along a great circle between two positions, instead of the rhumb line, will occur?
a) On north-south tracks at high low latitude.
b) On east-west tracks at low latitude.
c) On east-west tracks at high latitude.
d) On north-south tracks at low latitude.
40.
On the Earth's ellipsoid one degree of latitude near the equator is:
a) 60 nm.
b) More than 60 nm.
c) Less than 60 nm.
d) More than 60 nm but less than 61 nm.
41.
What is meant by "Aphelion"?
a) The point of the earth's orbit closest to the sun.
b) The point of the sun's orbit closest to the earth.
c) The point of the earth's orbit furthest away from the sun.
d) The point of the sun's orbit furthest away from the earth
42.
Geodetic latitude and Geographic latitude coincide?
a) Only at the poles.
b) at 45 N/S.
c) Only at the equator.
d) At the poles and on the equator.
43.
The lines on the earth's surface that join points of equal magnetic variation are called:
a) isogonals
b) isogrives
c) isoclines
d) isotachs
44.
Which definition of the equator is correct?
a) The equator is a great circle with its plane perpendicular to the earth's rotational axis.
b) The equator is a small circle with its plane perpendicular to the earth's rotational axis.
c) The equator is a great circle with its plane parallel to the earth's rotational axis.
d) The equator is a small circle with its plane parallel to the earth's rotational axis.
45.
An observer is situated on the parallel of latitude of 23.5S. Which statement about the passage of the apparent sun in relation to this position is correct?
a) It passes through the zenith once a year around March 21 st.
b) It passes through the zenith twice a year around June 21st and December 22nd.
c) It passes through the zenith twice a year March 21st and September 23rd.
d) It passes through the zenith once a year around December 22nd.
46.
The declination of the sun is defined as?
a) The arc of the meridian of the sun measured from the nearest pole to the sun.
b) The angular distance of the sun north or south of the celestial equator.
c) The arc from the celestial horizon to the sun measured along a vertical line perpendicular on the horizon.
d) The arc along the celestial sphere from zenith to the sun.
47.
Which statement about the duration of daylight is true?
a) In summer the length of the period of daylight decreases with increasing latitude.
b) Close to the equinoxes the influence of latitude on the duration of daylight is at its smallest.
c) Close to the solstices the influence of latitude on the duration of daylight is at its smallest.
d) On September 10th the duration of daylight is longer on the southern hemisphere than on the northern hemisphere.
48.
An aircraft is in position (86N 020E) . When following a rhumb line track of 085(T). It will?
a) Fly a spiral to the north pole.
b) Follow a small circle which lies to the north of the parallel of 86N.
c) Follow a line which lies at first to the north of the parallel of 86N but after having passed a DL of 180 degrees to the south of it.
d) Fly to the north pole via an arbitrary line.
49.
An aircraft is in position (86N 020E). When following a rhumb line track of 085(T) it will?
a) Follow a small circle which lies to the north of the parallel of 86N.
b) Fly to the north pole via an arbitrary line.
c) Follow a line which lies first to the north of the parallel of 86N but after having passed a DL of 180 to the south of it.
d) Fly via a spiral to the north pole.
50.
Kepler's second law states:
a) Each planet revolves so that the radius vector, sun to earth, sweeps out equal areas in equal intervals of time.
b) Each planet's radius vector, sun to earth, moves at a constant angular sped.
c) The area swept out by the radius vector of each planet, sun to earth, per hour, increasing with increasing length of the radius.
d) The length of the radius vector, sun to earth, is proportional to the square root of its angular sped.
51.
Which statement is correct about the apparent solar day?
a) The apparent solar day is the period between two successive transits of the true sun through the same meridian.
b) The duration of the apparent solar day is constant throughout the year due to the constant rotational speed of the earth.
c) The apparent solar day is the period between two successive transits of the mean sun through the same meridian.
d) The duration of the apparent solar day is constant throughout the year due to the constant velocity of the earth in its orbit.
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