Motion of the Earth – NDA Geography PYQs

NDA 2025-I

Q. 1. Which one of the following latitudes will experience a minimum angle of the Sun’s rays when it is Summer Solstice in the Northern Hemisphere?

(a) Arctic Circle

(b) Equator

(c) Tropic of Cancer

(d) Tropic of Capricorn

Answer: (d) Tropic of Capricorn

Explanation: At the Summer Solstice in the Northern Hemisphere (around June 21), the Sun is directly overhead at the Tropic of Cancer (23.5°N). The sun angle increases as you move toward the Tropic of Cancer from either direction. The Tropic of Capricorn (23.5°S) is on the opposite side of the equator from the Sun’s zenith position. It is the farthest inhabited latitude from the sun’s overhead position during the Northern Hemisphere summer. Therefore, the angle of the Sun’s rays is at a minimum at the Tropic of Capricorn: the Sun is at its lowest angle in the sky. Concept Tested: Summer Solstice in NH: Sun overhead at Tropic of Cancer; minimum sun angle (most oblique rays) at Tropic of Capricorn

NDA 2022-II

Q. 2. Which one of the following cities of the world would represent the greatest linear velocity of rotation of the Earth?

(a) Kampala, Uganda

(b) St. Petersburg, Russia

(c) Madrid, Spain

(d) Stockholm, Sweden

Answer: (a) Kampala, Uganda

Explanation: The linear (tangential) velocity of Earth’s rotation is greatest at the equator (latitude 0°) and decreases towards the poles. Linear velocity = radius × angular velocity. At the equator, the radius is maximum (about 6,378 km). At the poles, the effective radius is zero. Kampala, Uganda (~0.3°N) is the closest to the equator among the four cities, giving it the highest linear rotational velocity (~1,669 km/h at the equator). St. Petersburg (~60°N), Madrid (~40°N), and Stockholm (~59°N) are all at higher latitudes and have lower linear velocities. Concept Tested: Greatest linear rotational velocity: at the equator (latitude 0°); Kampala, Uganda is closest to the equator

NDA 2022-I

Q. 3. In a group discussion on shape and size of the Earth, three students stated the following points:

Student 1: The shape of the Earth is basically an oblate spheroid.

Student 2: The polar diameter of the Earth is more than the equatorial diameter.

Student 3: Bulge along the equatorial region is due to revolution of the Earth.

Who among the above students is/are correct?

(a) Student 1 only

(b) Student 1 and Student 2 only

(c) Student 2 and Student 3 only

(d) Student 1, Student 2 and Student 3

Answer: (a) Student 1 only

Explanation: Student 1 (Earth is an oblate spheroid): Correct. Earth is an oblate spheroid: flattened at the poles and bulging at the equator. Student 2 (Polar diameter > Equatorial diameter): Incorrect. The EQUATORIAL diameter (~12,756 km) is larger than the polar diameter (~12,714 km). Polar is smaller, not larger. Student 3 (Equatorial bulge due to revolution): Incorrect. The equatorial bulge is caused by Earth’s ROTATION on its axis: centrifugal force during rotation pushes matter outward at the equator. Revolution (orbit around the Sun) has nothing to do with the equatorial bulge. Concept Tested: Earth’s shape: oblate spheroid; equatorial > polar diameter; bulge due to ROTATION (not revolution)

Q. 4. Inhabitants are unaware of the speed of rotation of planet Earth because:

1. the angular velocity is constant for each place on the Earth’s surface

2. the atmosphere rotates with the Earth

3. there are no nearby objects, either stationary or moving at a rate different from that of the Earth

Which of the above is/are the correct explanation(s)?

(a) 1 only

(b) 1 and 2 only

(c) 2 and 3 only

(d) 1, 2 and 3

Answer: (d) 1, 2 and 3

Explanation: All three explanations are correct: 1. Angular velocity is constant: every point on Earth rotates at the same angular speed (360°/24 hours), so there is no relative rotation to perceive. 2. The atmosphere rotates with the Earth: we don’t feel the air rushing past us from a “stationary” atmosphere, because the air is moving with us. 3. No nearby reference objects: to perceive motion, we need nearby objects moving differently. Space provides no such reference at human scale. Concept Tested: Why we don’t feel Earth’s rotation: constant angular velocity, co-rotating atmosphere, no nearby reference objects

NDA 2019-I

Q. 5. Which one of the following is/are environmental effects of Rotation of the Earth?

1. Daily or diurnal rhythm in day-light and air temperature

2. Flow path of both air and water are turned consistently in a side-ward direction

3. The movement of the tides

Select the correct answer using the code given below:

(a) 1 and 2 only

(b) 1 and 3 only

(c) 1, 2 and 3

(d) 3 only

Answer: (a) 1 and 2 only

Explanation: Effect 1 (Diurnal rhythm in daylight and temperature): Correct. Rotation causes the cycle of day and night, which creates daily patterns of light and temperature. Effect 2 (Sideward deflection of air and water flow): Correct. This is the Coriolis effect, caused by Earth’s rotation. It deflects wind and ocean currents to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. Effect 3 (Tides): Incorrect. Tides are caused primarily by the gravitational pull of the Moon (and secondarily the Sun): not by Earth’s rotation. Rotation influences the timing of tides at a given location, but the creation of tidal bulges is due to gravity, not rotation. Concept Tested: Effects of Earth’s rotation: day/night cycle and Coriolis effect YES; tides are caused by Moon’s gravity, NOT rotation

NDA 2017-II

Q. 6. The shortest day length that occurs in the Northern Hemisphere is on:

(a) 21st March

(b) 23rd September

(c) 22nd November

(d) 22nd December

Answer: (d) 22nd December

Explanation: In the Northern Hemisphere, the shortest day (fewest hours of daylight) occurs on the Winter Solstice: approximately December 21–22. On this day, the Sun is at its southernmost position (overhead at Tropic of Capricorn), and the Northern Hemisphere is tilted maximally away from the Sun. March 21 and September 23 are equinoxes: day and night are approximately equal (12 hours each). Concept Tested: Shortest day in Northern Hemisphere: December 22 (Winter Solstice); Sun overhead at Tropic of Capricorn

NDA 2016-II

Q. 7. During solar eclipse:

(a) the Earth comes in between the Sun and the Moon

(b) the Moon comes in between the Sun and the Earth

(c) the Moon comes exactly halfway between the Earth and the Sun

(d) the Sun comes in between the Earth and the Moon

Answer: (b) The Moon comes in between the Sun and the Earth

Explanation: During a solar eclipse, the Moon passes between the Sun and Earth, blocking the Sun’s light from reaching Earth (or a part of it). The sequence: Sun → Moon → Earth. If the Moon is perfectly aligned, it blocks the entire disc of the Sun (total solar eclipse). If only part is blocked, it is a partial solar eclipse. (a) describes a lunar eclipse (Earth between Sun and Moon). (c) and (d) are incorrect configurations. Concept Tested: Solar eclipse: Moon between Sun and Earth; blocks sunlight from reaching Earth

NDA 2016-I

Q. 8. Which of the following statements in the context of Northern Hemisphere is/are correct?

1. Vernal equinox occurs on March 21.

2. Summer solstice occurs on December 22.

3. Autumnal equinox occurs on September 23.

4. Winter solstice occurs on June 21.

Select the correct answer using the code given below:

(a) 1 only

(b) 1 and 3 only

(c) 2 and 4 only

(d) 1, 2 and 3 only

Answer: (b) 1 and 3 only

Explanation: In the Northern Hemisphere: Statement 1 (Vernal equinox = March 21): Correct ✓. Statement 2 (Summer solstice = December 22): Incorrect. December 22 is the WINTER solstice in the Northern Hemisphere (Summer solstice in the Southern Hemisphere). Summer solstice in the NH = June 21. Statement 3 (Autumnal equinox = September 23): Correct ✓. Statement 4 (Winter solstice = June 21): Incorrect. June 21 is the SUMMER solstice in the Northern Hemisphere. Concept Tested: Northern Hemisphere seasonal dates: March 21 (Vernal equinox) and September 23 (Autumnal equinox) are correct

★ JOVIK Exam Insight Seasonal dates for NDA (Northern Hemisphere): March 21 → Vernal (Spring) Equinox: Sun overhead at Equator. June 21 → Summer Solstice: Sun overhead at Tropic of Cancer; longest day. September 23 → Autumnal Equinox: Sun overhead at Equator. December 22 → Winter Solstice: Sun overhead at Tropic of Capricorn; shortest day. These dates are REVERSED for the Southern Hemisphere (June = winter, December = summer).

NDA 2015-II

Q. 9. According to the Geo-scientists, the shape of the Earth is:

1. round

2. spherical

3. close to that of a sphere

4. an oblate ellipsoid

Select the correct answer using the code given below:

(a) 2, 3 and 4

(b) 1, 2 and 3

(c) 1 and 2 only

(d) 3 and 4 only

Answer: (d) 3 and 4 only

Explanation: Geo-scientists describe the Earth’s shape as: “Close to that of a sphere” (3): a useful approximation that acknowledges slight deviations. “An oblate ellipsoid” (4): the technically precise description. An oblate ellipsoid (or oblate spheroid) is a sphere slightly flattened at the poles and bulging at the equator. Earth’s equatorial diameter (~12,756 km) is slightly larger than its polar diameter (~12,714 km). “Round” (1) and “spherical” (2) are too general or technically imprecise. A perfect sphere would have equal diameters in all directions, which Earth does not. Concept Tested: Earth’s shape: oblate ellipsoid (oblate spheroid); equatorial bulge makes it not a perfect sphere

NDA 2015-I

Q. 10. To a perpendicular to the plane of ecliptic, Earth’s axis of rotation makes an angle of 23½°. Had this angle been zero degree, which one among the following would result?

(a) There would have been no season

(b) The length of day and night would have been the same throughout the year

(c) The length of the day and night would have been the same all over the earth

(d) All of the above

Answer: (d) All of the above

Explanation: If Earth’s axial tilt were 0° (perpendicular axis): (a) No seasons: the sun would be directly overhead at the equator year-round, giving no variation in the amount of sunlight received by any latitude. Correct. (b) Day and night would be equal (12 hours each) throughout the year at all locations. Correct. (c) Day and night would be the same (12 hours each) all over the Earth at all times. Correct. All three consequences would follow from a zero-degree axial tilt. Answer: All of the above. Concept Tested: Zero axial tilt consequence: no seasons, equal day/night everywhere and throughout the year

NDA 2014-I

Q. 11. The summer and winter seasons in a year are caused by:

(a) aphelion (farthest) and perihelion (nearest) positions of the Earth from the Sun during the annual revolution

(b) rotation of the Earth on its axis

(c) variation in solar insolation

(d) revolution of the Earth on its inclined axis

Answer: (d) revolution of the Earth on its inclined axis

Explanation: Seasons are caused by the combination of two factors: Earth’s revolution around the Sun AND the axial tilt of 23.5°. Together, these cause different parts of Earth to receive different amounts of sunlight at different times of year. Option (a) is a common misconception: Earth is closest to the Sun (perihelion) in January (northern hemisphere winter!): so distance from the Sun does NOT cause seasons. Option (b) Rotation causes day and night: not seasons. Option (c) Solar insolation varies because of the tilt and revolution, but this is the effect, not the cause. Concept Tested: Seasons are caused by Earth’s revolution on its inclined axis (23.5° tilt), not by distance from the Sun

★ JOVIK Exam Insight A very common NDA trap: students think seasons are caused by Earth’s distance from the Sun (closer = summer). This is WRONG. In January (Northern Hemisphere winter), Earth is actually closest to the Sun (perihelion). Seasons are caused by the axial tilt of 23.5° combined with revolution around the Sun.

NDA 2011-I

Q. 12. If the Earth’s axis were perpendicular to the plane of its orbit, which one among the following would not have happened?

(a) The North Pole will always lie in dark

(b) Days and nights would be equal throughout the year

(c) No change of seasons will take place

(d) The sun will be perpendicular to the equator

Answer: (a) The North Pole will always lie in dark

Explanation: If the Earth’s axis were perpendicular (0° tilt) to its orbital plane: (b) Days and nights would be equal (12 hours each) everywhere throughout the year: this WOULD happen. (c) No seasons would occur because the sun would always be overhead at the equator: this WOULD happen. (d) The sun would always be perpendicular to the equator: this WOULD happen. (a) The North Pole lying always in dark would NOT happen. With a perpendicular axis, the sun would always be over the equator, and the poles would receive sunlight at a very low angle: but would not be in permanent darkness. (Currently, the North Pole experiences 6 months of darkness due to tilt.) With zero tilt, both poles would receive equal, low-angle sunlight year-round. Concept Tested: Zero axial tilt consequences: the North Pole would NOT be permanently dark; seasons and unequal days would disappear

NDA 2010-II

Q. 13. Consider the following statements:

I. The tropical year is shorter than the sidereal year.

II. The solar day is longer than the sidereal day.

Which of the statements given above is/are correct?

(a) I only

(b) II only

(c) Both I and II

(d) Neither I nor II

Answer: (c) Both I and II

Explanation: Statement I (Tropical year shorter than sidereal year): Correct. The tropical year (~365.24 days) is slightly shorter than the sidereal year (~365.26 days) due to the precession of the equinoxes: a slow wobble of Earth’s axis. Statement II (Solar day longer than sidereal day): Correct. The sidereal day is ~23 hours 56 minutes (Earth’s rotation relative to fixed stars). The solar day is 24 hours (Earth’s rotation relative to the Sun). The solar day is longer because Earth must rotate slightly extra to bring the Sun back to the same position, as Earth is also moving along its orbit. Concept Tested: Sidereal vs. solar measurements: tropical year < sidereal year; solar day > sidereal day

NDA 2009-II

Q. 14. Consider the following statements:

1. The vernal equinox falls on March 21.

2. On equinox, the sun is directly overhead at the equator.

3. The changes in the day length on equinox result from the changes in the tilt of the earth with respect to the sun.

Which of the statements given above is/are correct?

(a) 1 and 2

(b) 1 only

(c) 1, 2 and 3

(d) 2 and 3

Answer: (a) 1 and 2

Explanation: Statement 1: Correct. The vernal (spring) equinox in the Northern Hemisphere occurs on or around March 21. Statement 2: Correct. On both equinoxes (March and September), the sun is directly overhead at the Equator, making day and night approximately equal all over the world. Statement 3: Incorrect. On an equinox, the day length is approximately 12 hours everywhere: not “changing”. Statement 3 implies day length changes on the equinox, which is not precise. Equinoxes are defined by equal day and night, not by changing lengths. Changes in day length occur in the weeks/months around the equinox, not on the equinox itself. Concept Tested: Equinox facts: March 21 vernal equinox; sun overhead at equator; day ≈ night; Statement 3 is imprecise

Q. 15. Consider the following statements:

1. The Earth’s rotation axis is not at 90° to its orbital plane.

2. The Earth’s rotation axis is inclined at 23.5°.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Answer: (c) Both 1 and 2

Explanation: Statement 1: Correct. The Earth’s rotation axis is tilted and is therefore NOT at 90° to its orbital plane (the plane of the ecliptic). If it were at 90°, there would be no tilt. Statement 2: Correct. The Earth’s axis is inclined at approximately 23.5° to the perpendicular of its orbital plane (or equivalently, at 66.5° to the orbital plane itself). This tilt causes the seasons. Concept Tested: Earth’s axial tilt: 23.5° from the perpendicular to the orbital plane; this causes seasons

NDA 2008-II

Q. 16. Which one of the following pairs is not correctly matched?

Month: Position of Sun

(a) June: Midday Sun overhead at Tropic of Cancer

(b) December: Midday Sun overhead at Tropic of Capricorn

(c) March: Midday Sun overhead at Equator

(d) September: Midday Sun overhead at Arctic Circle

Answer: (d) September: Midday Sun overhead at Arctic Circle

Explanation: The Sun is overhead (at zenith) only between the Tropic of Cancer and the Tropic of Capricorn. (a) June: Summer Solstice: Sun overhead at Tropic of Cancer (23.5°N). Correct ✓. (b) December: Winter Solstice: Sun overhead at Tropic of Capricorn (23.5°S). Correct ✓. (c) March: Vernal Equinox: Sun overhead at the Equator (0°). Correct ✓. (d) September: Autumnal Equinox: Sun is overhead at the Equator (0°), NOT at the Arctic Circle. The Arctic Circle is at 66.5°N: the Sun is never directly overhead there. This pair is incorrect. Concept Tested: Sun’s overhead position in different months: September = overhead at Equator (not Arctic Circle)

Q. 17. Foucault experiment is proof of which one of the following?

(a) Revolution of Earth

(b) Rotation of Earth

(c) Rotation of Moon

(d) Revolution of Moon

Answer: (b) Rotation of Earth

Explanation: The Foucault pendulum (demonstrated by Léon Foucault in Paris in 1851) is a direct proof of Earth’s rotation. A long pendulum is set swinging in a fixed plane. Over time, its plane of oscillation appears to rotate: but actually, the Earth rotates beneath it, and the pendulum continues swinging in a fixed direction in space. This apparent rotation proves Earth is rotating on its axis. Concept Tested: Foucault pendulum: experimental proof of Earth’s rotation on its own axis

Q. 18. Which one of the following is the time required for the Earth to return to a given point in its orbit with reference to fixed stars called?

(a) Lunar year

(b) Solar year

(c) Tropical year

(d) Sidereal year

Answer: (d) Sidereal year

Explanation: The Sidereal year is the time taken for the Earth to complete one revolution around the Sun with reference to fixed stars: approximately 365 days, 6 hours, 9 minutes, and 9.5 seconds. The Tropical year (solar year) is the time between successive vernal equinoxes: approximately 365 days, 5 hours, 48 minutes, and 46 seconds. It is slightly shorter than the sidereal year. Lunar year is based on the cycles of the Moon (about 354 days). Concept Tested: Sidereal year: Earth’s orbital period measured against fixed stars; slightly longer than the tropical year

★ JOVIK Exam Insight Types of year for NDA: Sidereal year (~365.25 days) → measured against fixed stars. Tropical/Solar year (~365.24 days) → measured between vernal equinoxes; slightly shorter. Lunar year (~354 days) → based on 12 lunar months. Calendar year = 365 days (leap year = 366). Sidereal day (~23h 56min) < Solar day (24h).

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