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Gravitation — Question 12

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Question 12

Gravitational force on the surface of the moon is only 16\dfrac{1}{6} as strong as gravitational force on the earth. What is the weight in newtons of a 10 kg object on the moon and on the earth?

Answer

Given,

Acceleration due to earth's gravity g = 9.8 ms-2

Object's mass, m = 10 kg

Acceleration due to moon gravity = gm

Weight on the earth = We

Weight on the moon = Wm

Weight = mass x gravity

gm = 16\dfrac{1}{6} ge (given)

So, Wm = m gm = m x 16\dfrac{1}{6} x ge

Wm = 10 x 16\dfrac{1}{6} x 9.8 = 16.34 N

We = m x ge = 10 x 9.8

We = 98 N

Hence, weight on moon and earth = 16.34 and 98 N respectively.

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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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