Gravitation is one of the most reliably tested topics in RRB Group D Physics — and also one of the easiest to score in if you prepare it the right way. The same 4–5 concept types repeat across exam years, making this chapter highly predictable.
Most students either over-prepare it (wasting time on derivations RRB never asks) or skip it entirely. This guide gives you exactly what the exam demands — concepts, formulas, and the MCQ patterns that actually appear.
🎯 Quick Answer (30-Second Read)
- Gravitation contributes 2–3 questions in RRB Group D CBT under General Science (Physics)
- Most tested formula: g = GM/R² — value of g at Earth's surface = 9.8 m/s²
- g decreases as you go higher (away from Earth's centre) or deeper underground
- g is zero at Earth's centre — a direct MCQ that appears repeatedly
- Universal Gravitational Constant G = 6.67 × 10⁻¹¹ Nm²/kg² — memorize this value
Source: RRB Group D Official Syllabus — indianrailways.gov.in
Core Gravitation Concepts RRB Actually Tests
RRB Group D does not test derivations or complex theory. Focus only on these three concept areas:
🔭 Newton's Law of Gravitation
Every two objects attract each other with a force F = Gm₁m₂/r².
The key exam insight — if distance doubles, gravitational force becomes one-fourth (inverse square relationship).
📉 Acceleration Due to Gravity (g)
This is the most tested concept in RRB Group D Gravitation. The value g = 9.8 m/s² applies at Earth's surface.
- g decreases as altitude increases
- g decreases as you go deeper underground
- g is maximum at poles and minimum at equator
- g is zero at Earth's centre
🔄 Difference Between g and G
G is the universal gravitational constant — same everywhere in the universe. g is acceleration due to gravity — varies by location.
RRB asks this distinction directly as an MCQ almost every cycle.
Must-Know Gravitation Formulas
| Concept | Formula / Value |
|---|---|
| Gravitational Force | F = Gm₁m₂/r² |
| Value of g (Earth surface) | 9.8 m/s² |
| g on Moon | 1.63 m/s² (1/6th of Earth) |
| Universal Constant G | 6.67 × 10⁻¹¹ Nm²/kg² |
| Escape Velocity (Earth) | 11.2 km/s |
| Orbital Velocity | v = √(gR) |
Source: NCERT Class 9 Science, Chapter 10 — Gravitation
Anjali from Lucknow scored 31/35 in RRB Group D Science (2022) by making a one-page sheet of exactly these values and revising it daily for one week before the exam.
High-Frequency MCQ Patterns to Practice
RRB setters return to the same question types year after year. Practice these specifically:
📍 "Where is g maximum/minimum on Earth?"
→ Maximum at poles, minimum at equator
🌙 "What happens to weight on Moon?"
→ Weight becomes 1/6th; mass stays the same
🌍 "What is the value of g at Earth's centre?"
→ Zero
⚖️ "If mass doubles, what happens to gravitational force?"
→ Force doubles (directly proportional)
🚀 "What is escape velocity from Earth?"
→ 11.2 km/s
Weight vs Mass is another trap question — weight changes with location (depends on g), but mass never changes. This distinction appears in at least one question per exam cycle.
People Also Search For
What are the important formulas in gravitation?
Key formulas include gravitational force (F = G \frac{m_1 m_2}{r^2}), acceleration due to gravity (g = \frac{GM}{R^2}), potential energy (U = -\frac{GMm}{r}), and weight (W = mg). These formulas are widely used in numerical problems. Understanding their application is essential. Regular practice improves accuracy.
What is (F = G \frac{m_1 m_2}{r^2}) in gravitation?
This is Newton's law of gravitation which states that the force between two masses is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. Here, G is the universal gravitational constant. This formula explains attraction between objects. Concept clarity helps in solving questions.
How is (g = 9.8 , m/s^2) derived?
The value of (g) is derived using the formula (g = \frac{GM}{R^2}), where M is Earth's mass and R is its radius. Substituting known values gives approximately 9.8 m/s². This represents the acceleration experienced by objects near Earth's surface. Understanding derivation helps in conceptual clarity.
What types of gravitation MCQs are asked in exams?
Questions may include formula-based problems, conceptual understanding of gravitational force, variation of g with height or depth, and numerical calculations. Candidates should focus on applying formulas correctly. Practising MCQs improves speed and confidence.
Why is gravitation an important topic for competitive exams?
Gravitation is a fundamental topic in physics and is frequently asked in objective exams. It helps in understanding motion of planets and objects under force. Strong conceptual knowledge improves performance in numerical questions. Regular revision strengthens preparation.
Conclusion: Your Next Step
RRB Group D Gravitation rewards students who prepare smart, not long. Focus on the 6 key values, 3 core concepts, and the 5 MCQ patterns above — that covers everything this exam has ever asked from this chapter.
Ready to crack RRB Group D Physics end-to-end? Explore PrepGrind's RRB Group D Science module — chapter-wise MCQ banks, previous year question analysis, and revision notes built for serious aspirants.