Gravitation – Diagram Based & Long Answer Questions

Stage 2 • Page 5 • 3–5 Mark Board Questions

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Question 1 (Diagram-Based)

Q: Draw a neat diagram showing variation of acceleration due to gravity with depth inside the Earth and explain.

Answer:

Acceleration due to gravity decreases as we move towards the centre of Earth and becomes zero at the centre.

• At surface: g = maximum
• At depth d: g = g₀(1 − d/R)
• At centre: g = 0

Note to Student: Always label surface, centre, and axis clearly in the diagram.

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Question 2 (3 Marks)

Q: State Newton’s law of gravitation and write its mathematical expression.

Answer:

Newton’s law of gravitation states that every two masses in the universe attract each other with a force directly proportional to the product of their masses and inversely proportional to the square of distance between their centres.

F = G(m₁m₂ / r²)

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Question 3 (3 Marks)

Q: Define escape velocity. Write its expression.

Answer:

Escape velocity is the minimum velocity required by a body to escape from the gravitational field of a planet without any further propulsion.

v_e = √(2GM/R)

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Question 4 (5 Marks)

Q: Derive the expression for acceleration due to gravity on the surface of Earth.

Answer:

1. According to Newton’s law: F = GMm/R²
2. Force on body = Weight = mg
3. Equating: mg = GMm/R²
4. Cancel m on both sides
5. g = GM/R²

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Question 5 (5 Marks)

Q: Why is escape velocity independent of mass of the object?

Answer:

Escape velocity depends only on gravitational field strength of the planet (mass and radius). Mass of the escaping body cancels during derivation, so escape velocity is independent of mass.

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Examiner’s Expectation

• Neat diagrams with labels
• Correct formulas
• Stepwise derivation
• No unnecessary theory

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Stage 2 • Page 5 Completed Successfully ✅