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Q70 (IAS/2015) Geography › World Physical Geography › Ocean circulation systems Official Key

Tides occur in the oceans and seas due to which among the following? 1. Gravitational force of the Sun 2. Gravitational force of the Moon 3. Centrifugal force of the Earth Select the correct answer using the code given below.

Result
Your answer: —  ·  Correct: D
Explanation

Tides are the periodical rise and fall of sea level, once or twice a day, mainly due to the attraction of the sun and the moon.[2] The moon's gravitational pull to a great extent and to a lesser extent the sun's gravitational pull, are the major causes for the occurrence of tides.[2] Additionally, centrifugal force, which is the force that acts to counter balance gravity, is another factor.[2]

Together, the gravitational pull and the centrifugal force are responsible for creating the two major tidal bulges on the earth.[3] On the side facing the moon, a tidal bulge occurs, while on the opposite side, though the moon's gravitational attraction is less, the centrifugal force causes a tidal bulge.[3]

Therefore, all three factors—the gravitational force of the Sun, the gravitational force of the Moon, and the centrifugal force of the Earth—contribute to the occurrence of tides. The correct answer is option D (1, 2 and 3).

Sources
  1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > 32.2. Tides > p. 500
  2. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > TIDES > p. 109
  3. [3] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > TIDES > p. 109
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Don’t just practise – reverse-engineer the question. This panel shows where this PYQ came from (books / web), how the examiner broke it into hidden statements, and which nearby micro-concepts you were supposed to learn from it. Treat it like an autopsy of the question: what might have triggered it, which exact lines in the book matter, and what linked ideas you should carry forward to future questions.
Q. Tides occur in the oceans and seas due to which among the following? 1. Gravitational force of the Sun 2. Gravitational force of the Mo…
At a glance
Origin: From standard books Fairness: High fairness Books / CA: 10/10 · 0/10

This is a textbook 'Sitter' directly from NCERT Class XI. It rewards careful reading of definitions rather than skimming. The strategy is simple: In Physical Geography, if a process involves forces, list ALL contributing forces mentioned in the text, not just the dominant one.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
Are tides in the oceans and seas caused by the gravitational force of the Sun?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > 32.2. Tides > p. 500
Presence: 5/5
“• The periodical rise and fall of the sea level, once or twice a day, mainly due to the attraction of the sun and the moon, is called a tide. The study of tides is very complex, spatially and temporally, as it has great variations in frequency, magnitude and height.• The moon's gravitational pull to a great extent and to a lesser extent the sun's, are the major causes for the occurrence of tides. Another factor is the centrifugal force (which arises due to the rotation of”
Why this source?
  • Explicitly states tides are due to attraction of the sun and the moon.
  • Specifies the moon's pull is dominant and the sun's pull contributes to a lesser extent.
FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > TIDES > p. 109
Presence: 5/5
“The periodical rise and fall of the sea level, once or twice a day, mainly due to the attraction of the sun and the moon, is called a tide. Movement of water caused by meteorological effects (winds and atmospheric pressure changes) are called surges. Surges are not regular like tides. The study of tides is very complex, spatially and temporally, as it has great variations in frequency, magnitude and height. The moon's gravitational pull to a great extent and to a lesser extent the sun's gravitational pull, are the major causes for the occurrence of tides. Another factor is centrifugal force, which is the force that acts to counter balance the gravity.”
Why this source?
  • Defines tides as caused mainly by attraction of the sun and moon.
  • Clearly notes the moon's gravitational pull is greater, with the sun's pull being a secondary cause.
FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > Tides based on the Sun, Moon and the Earth Positions > p. 110
Presence: 5/5
“At this time the sun and moon are at right angles to each other and the forces of the sun and moon tend to counteract one another. The Moon's attraction, though more than twice as strong as the sun's, is diminished by the counteracting force of the sun's gravitational pull. Once in a month, when the moon's orbit is closest to the earth (perigee), unusually high and low tides occur. During this time the tidal range is greater than normal. Two weeks later, when the moon is farthest from earth (apogee), the moon's gravitational force is limited and the tidal ranges are less than their average heights.”
Why this source?
  • Explains interaction of sun and moon forces (e.g., right-angle configuration reduces combined effect).
  • States the moon's attraction is stronger than the sun's but acknowledges the sun's gravitational pull affects tidal range.
Statement 2
Are tides in the oceans and seas caused by the gravitational force of the Moon?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > 32.2. Tides > p. 500
Presence: 5/5
“• The periodical rise and fall of the sea level, once or twice a day, mainly due to the attraction of the sun and the moon, is called a tide. The study of tides is very complex, spatially and temporally, as it has great variations in frequency, magnitude and height.• The moon's gravitational pull to a great extent and to a lesser extent the sun's, are the major causes for the occurrence of tides. Another factor is the centrifugal force (which arises due to the rotation of”
Why this source?
  • Explicitly states tides are mainly due to the attraction of the moon (and to a lesser extent the sun).
  • Identifies gravitational pull as a primary cause of periodic sea-level rise and fall.
FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > TIDES > p. 109
Presence: 5/5
“Together, the gravitational pull and the centrifugal force are responsible for creating the two major tidal bulges on the earth. On the side of the earth facing the moon, a tidal bulge occurs while on the opposite side though the gravitational attraction of the moon is less as it is farther away, the centrifugal force causes tidal bulge on the other side (Figure 13.2). The 'tide-generating' force is the difference between these two forces; i.e. the gravitational attraction of the moon and the centrifugal force. On the surface of the earth, nearest the moon, pull or the attractive force of the moon is greater than the centrifugal force, and so there is a net force causing a bulge towards the moon.”
Why this source?
  • Explains the mechanism: gravitational pull of the moon together with centrifugal force produces the two major tidal bulges.
  • Describes how net (tide‑generating) force arises from difference between moon's attraction and centrifugal force, producing a bulge toward the moon.
FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > Tides based on the Sun, Moon and the Earth Positions > p. 110
Presence: 5/5
“At this time the sun and moon are at right angles to each other and the forces of the sun and moon tend to counteract one another. The Moon's attraction, though more than twice as strong as the sun's, is diminished by the counteracting force of the sun's gravitational pull. Once in a month, when the moon's orbit is closest to the earth (perigee), unusually high and low tides occur. During this time the tidal range is greater than normal. Two weeks later, when the moon is farthest from earth (apogee), the moon's gravitational force is limited and the tidal ranges are less than their average heights.”
Why this source?
  • States the moon's attraction is more than twice as strong as the sun's, reinforcing the moon's dominant role.
  • Relates lunar distance (perigee/apogee) to variation in tidal range, linking moon's gravity to observable tidal strength.
Statement 3
Are tides in the oceans and seas caused by the centrifugal force of the Earth?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > TIDES > p. 109
Presence: 5/5
“Together, the gravitational pull and the centrifugal force are responsible for creating the two major tidal bulges on the earth. On the side of the earth facing the moon, a tidal bulge occurs while on the opposite side though the gravitational attraction of the moon is less as it is farther away, the centrifugal force causes tidal bulge on the other side (Figure 13.2). The 'tide-generating' force is the difference between these two forces; i.e. the gravitational attraction of the moon and the centrifugal force. On the surface of the earth, nearest the moon, pull or the attractive force of the moon is greater than the centrifugal force, and so there is a net force causing a bulge towards the moon.”
Why this source?
  • Explicitly states tidal bulges result from combined gravitational pull and centrifugal force.
  • Explains centrifugal force produces the bulge on the side opposite the Moon and that tide-generating force is the difference between gravity and centrifugal force.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > 32.2. Tides > p. 500
Presence: 4/5
“• The periodical rise and fall of the sea level, once or twice a day, mainly due to the attraction of the sun and the moon, is called a tide. The study of tides is very complex, spatially and temporally, as it has great variations in frequency, magnitude and height.• The moon's gravitational pull to a great extent and to a lesser extent the sun's, are the major causes for the occurrence of tides. Another factor is the centrifugal force (which arises due to the rotation of”
Why this source?
  • Identifies the Moon's (major) and Sun's (minor) gravitational pulls as main causes and lists centrifugal force as an additional factor.
  • Indicates centrifugal force arises due to rotation and contributes to tidal phenomena alongside gravitational forces.
Pattern takeaway: UPSC Physical Geography questions often test 'Completeness of Cause'. They know you know the Moon causes tides. They ask this to check if you know the Sun and Earth's rotation (Centrifugal force) also play non-negotiable roles. Expect 'All of the above' in multi-factor physical processes.
How you should have studied
  1. [THE VERDICT]: Sitter. Direct lift from NCERT Class XI Fundamentals of Physical Geography, Chapter 13 (Movements of Ocean Water).
  2. [THE CONCEPTUAL TRIGGER]: Oceanography > Tides > Mechanism of Formation (Gravitational vs Centrifugal balance).
  3. [THE HORIZONTAL EXPANSION]: Memorize the sibling terms: Syzygy (Straight line = Spring Tides), Quadrature (Right angle = Neap Tides), Perigee (Moon closest = High tidal range), Apogee (Moon farthest), and the concept of Tidal Bores (e.g., Hooghly river).
  4. [THE STRATEGIC METACOGNITION]: Don't stop at 'The Moon causes tides'. Always ask 'What else?'. NCERT explicitly mentions the Sun and Centrifugal force in the same paragraph. When studying physical phenomena, map the entire 'Force Vector' diagram mentally.
Concept hooks from this question
📌 Adjacent topic to master
S1
👉 Relative roles of Moon and Sun in generating tides
💡 The insight

Multiple references state tides arise from both moon and sun gravity, with the moon dominant and the sun a secondary contributor.

High-yield for UPSC physical geography: questions often ask which body is the principal cause and whether the sun contributes. Understanding the relative influence clarifies answers on tidal magnitude and periodicity; revise comparative statements and practice reasoned elimination in MCQs.

📚 Reading List :
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > 32.2. Tides > p. 500
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > TIDES > p. 109
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > Tides based on the Sun, Moon and the Earth Positions > p. 110
🔗 Anchor: "Are tides in the oceans and seas caused by the gravitational force of the Sun?"
📌 Adjacent topic to master
S1
👉 Spring and neap tides (alignment effects)
💡 The insight

References describe how sun–moon alignment (in line or at right angles) amplifies or diminishes tidal ranges.

Frequently tested concept linking celestial geometry to coastal phenomena. Mastering this enables quick answers on timing of highest/lowest tidal ranges, spring vs neap reasoning, and related coastal planning questions; use diagram practice and timeline sequences.

📚 Reading List :
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > Neap Tides > p. 504
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > Tides based on the Sun, Moon and the Earth Positions > p. 110
🔗 Anchor: "Are tides in the oceans and seas caused by the gravitational force of the Sun?"
📌 Adjacent topic to master
S1
👉 Centrifugal force and tidal friction effects
💡 The insight

Sources mention centrifugal force as an additional factor and tidal friction from tidal forces affecting Earth's rotation and bulging.

Useful for integrated questions connecting oceanography and geophysics (e.g., tidal bulges, Earth rotation slowdown). Understand the mechanics (gravity vs centrifugal effects) and long-term consequences to answer application-style and explanation-based questions; link diagrams with cause–effect statements.

📚 Reading List :
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > 32.2. Tides > p. 500
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > Tidal Friction > p. 59
🔗 Anchor: "Are tides in the oceans and seas caused by the gravitational force of the Sun?"
📌 Adjacent topic to master
S2
👉 Tide‑generating forces: gravity + centrifugal force
💡 The insight

References explain tides arise from the moon's gravitational pull combined with the centrifugal force from Earth–Moon rotation, which together create tidal bulges.

High-yield for physical geography questions: explains basic mechanism of tides and supports distinguishing tidal bulges’ causes. Connects to dynamics of Earth–Moon system and to other topics like tidal friction and rotational effects. Prepare by understanding force balance diagrams and being able to explain bulge formation succinctly.

📚 Reading List :
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > TIDES > p. 109
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > 32.2. Tides > p. 500
🔗 Anchor: "Are tides in the oceans and seas caused by the gravitational force of the Moon?"
📌 Adjacent topic to master
S2
👉 Relative roles of Moon and Sun; perigee/apogee effects
💡 The insight

Evidence notes the moon's attraction dominates over the sun's and that lunar distance (perigee/apogee) affects tidal ranges.

Frequently tested in questions on spring/neap tides and tidal magnitude variations; helps answer why spring tides occur and why some monthly tides are unusually high. Study by comparing gravitational influence magnitudes and linking lunar phases/positions to tidal outcomes.

📚 Reading List :
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > Tides based on the Sun, Moon and the Earth Positions > p. 110
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > 32.2. Tides > p. 500
🔗 Anchor: "Are tides in the oceans and seas caused by the gravitational force of the Moon?"
📌 Adjacent topic to master
S2
👉 Local amplification: barrier and funneling effects on tides
💡 The insight

Sources state horizontal tide‑generating forces and coastal geometry (barrier/funnelling) can magnify tidal heights, affecting observed tidal ranges.

Important for applied UPSC questions on regional tidal extremes (e.g., Bay of Fundy) and coastal management. Connects physical oceanography with coastal geomorphology and human impacts. Learn typical examples and the morphological controls that amplify tides.

📚 Reading List :
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > Characteristics of Tides > p. 508
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > 32.2. Tides > p. 500
🔗 Anchor: "Are tides in the oceans and seas caused by the gravitational force of the Moon?"
📌 Adjacent topic to master
S3
👉 Tide-generating forces: gravity vs centrifugal
💡 The insight

References explain tides arise from the interplay of gravitational attraction (Moon and Sun) and centrifugal force; the net ('tide-generating') force is the difference between them.

High-yield for UPSC geography: questions often ask causes of tides and require nuance (not just 'centrifugal' or 'gravity'). Connects to lunar-solar alignment topics (spring/neap tides) and dynamic Earth processes. Master by comparing force vectors and practising short explanations that state primary vs secondary roles.

📚 Reading List :
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > TIDES > p. 109
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > 32.2. Tides > p. 500
🔗 Anchor: "Are tides in the oceans and seas caused by the centrifugal force of the Earth?"
🌑 The Hidden Trap

The '50-Minute Delay': While tides occur twice a day, they don't happen at the same time. A tidal day is 24 hours and 50 minutes because the Moon orbits the Earth in the same direction as Earth's rotation. This specific time lag is a high-probability future statement.

⚡ Elimination Cheat Code

The 'Universal Physics' Logic: Gravity is a universal force; it doesn't switch off. If the Sun has mass, it MUST exert pull (Statement 1 is true). If the Earth rotates, Centrifugal force MUST exist (Statement 3 is true). In physical geography, unless a factor is explicitly negligible, fundamental forces usually act together. Go with 'All of the above'.

🔗 Mains Connection

Mains GS-3 (Energy & Infrastructure): Link tidal mechanisms to 'Tidal Energy Potential' in India (Gulf of Khambhat, Gulf of Kutch, Sunderbans). Also, link to 'Tidal Ports' (e.g., Kandla, Diamond Harbour) where navigation depends on high tide timing—crucial for trade logistics.

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SIMILAR QUESTIONS

CDS-I · 2018 · Q16 Relevance score: 1.32

Statement I : Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth. Statement I : The Earth rotates from west to east.

CAPF · 2025 · Q77 Relevance score: 0.43

Consider the following statements with reference to neap tides: 1. Normally, there is a seven-day interval between two neap tides. 2. At this time, the Sun and the Moon are at right angles to each other. 3. The Moon's attraction is diminished by the counteracting force of the Sun's gravitational pull. Which of the statements given above is/are correct?

NDA-I · 2019 · Q6 Relevance score: -0.75

Spring tides refer to

CDS-I · 2009 · Q67 Relevance score: -0.87

Which one of the following is the tide produced as a consequence of moon and sun pulling the earth in the same direction ?