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Gravitation — Question 16

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Question 16

Calculate the force of gravitation between the earth and the Sun, given that the mass of the earth = 6 × 1024 kg and of the Sun = 2 × 1030 kg. The average distance between the two is 1.5 × 1011 m.

Answer

Given,

Mass of the sun (m) = 2 × 1030 kg

Mass of the earth (M) = 6 × 1024 kg

G = 6.67 x 10-11 Nm2kg-2

Average distance R = 1.5 × 1011 m

According to the formula for gravitational force we know,

F = G MmR2\dfrac{\text{M}\text{m}}{\text{R}^2}

Substituting we get,

F = 6.67×10−11×6×1024×2×1030(1.5×1011)2\dfrac{6.67 \times 10^{-11}\times 6 \times 10^{24} \times 2 \times 10^{30} }{(1.5 \times 10^{11})^2} = 3.56 x 1022 N

Hence, magnitude of the gravitational force = 3.56 x 1022 N

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Science | Chapter 9: GravitationWeb Content — Quick Reference

Chapter 9: Gravitation — Quick Reference

universal law gravity mass weight pressure buoyancy Archimedes principle relative density

Quick Revision Points

  • F = Gm₁m₂/r² (G = 6.674 × 10⁻¹¹ N·m²/kg²)
  • g = GM/R² = 9.8 m/s² (Earth); g on Moon ≈ g/6
  • Mass (kg, constant) vs Weight (N = mg, varies with location)
  • Pressure P = F/A (Pa = N/m²); Fluid pressure P = hρg
  • Archimedes: buoyant force = weight of displaced fluid
  • Float if density < fluid density; Sink if density > fluid density
  • Relative density = density of substance / density of water (no unit)
Exam Tips for Chapter 9
  • Read the detailed chapter notes for complete coverage of all NCERT topics.
  • Practice all NCERT in-text and back exercise questions — they are frequently asked in exams.
  • Focus on comparison tables, diagrams, and definitions — these are high-scoring areas.
  • For numericals (if applicable), practice at least 20 problems of varying difficulty.
  • Refer to the practice question bank (200+ questions) for thorough preparation.
Related Resources
  • Detailed Notes: ch09-gravitation.html
  • Practice Questions: 100+ questions with answers in 05-practice-questions/
  • Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
  • Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html
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