What is the difference between G and g?

G (Universal Gravitational Constant) = 6.67 × 10⁻¹¹ N·m²/kg² — constant everywhere in the universe. g (acceleration due to gravity) = 9.8 m/s² — varies with location (less on Moon, zero in space). G is used in F = Gm₁m₂/r²; g is used in W = mg and equations of free fall.

Why does an object fall faster on Earth than on the Moon?

On Earth, g = 9.8 m/s². On the Moon, g_moon = 1.6 m/s² (about 1/6 of Earth's g) because the Moon has less mass and smaller radius. So the same object falls slower on the Moon. An object dropped from the same height takes longer to fall on the Moon than on Earth.

State Archimedes' Principle and one application.

Archimedes' Principle: When a body is immersed in a fluid, it experiences an upward buoyant force equal to the weight of fluid displaced. Application: Ships are designed to displace water equal to their total weight, so the buoyant force equals weight and the ship floats. When loaded, the ship sinks deeper to displace more water.

Universal Law of Gravitation

Gravitation • Class 9 Science • NCERT • CBSE

Newton's Universal Law of Gravitation states that every object in the universe attracts every other object with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them: F = Gm₁m₂/r².

Key Formulas

F = Gm₁m₂/r² (Universal Law of Gravitation)
G = 6.67 × 10⁻¹¹ N·m²/kg²
g = 9.8 m/s² ≈ 10 m/s² (acceleration due to gravity)
W = mg (Weight = mass × g)
h = ½gt² (free fall from rest)
v = u + gt, h = ut + ½gt², v² = u² + 2gh

Frequently Asked Questions

What is the difference between G and g?: G (Universal Gravitational Constant) = 6.67 × 10⁻¹¹ N·m²/kg² — constant everywhere in the universe. g (acceleration due to gravity) = 9.8 m/s² — varies with location (less on Moon, zero in space). G is used in F = Gm₁m₂/r²; g is used in W = mg and equations of free fall.
Why does an object fall faster on Earth than on the Moon?: On Earth, g = 9.8 m/s². On the Moon, g_moon = 1.6 m/s² (about 1/6 of Earth's g) because the Moon has less mass and smaller radius. So the same object falls slower on the Moon. An object dropped from the same height takes longer to fall on the Moon than on Earth.
State Archimedes' Principle and one application.: Archimedes' Principle: When a body is immersed in a fluid, it experiences an upward buoyant force equal to the weight of fluid displaced. Application: Ships are designed to displace water equal to their total weight, so the buoyant force equals weight and the ship floats. When loaded, the ship sinks deeper to displace more water.

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