Gravitation

What is Gravitation?

⭐ What is Gravitation?

• Gravitation is the force of attraction between any two objects in the universe. 🌌
• This universal attraction is known as gravitational force.

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🧲 Newton’s Universal Law of Gravitation

Sir Isaac Newton stated 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.” 📘

📍 Formula:

F = G^m1m2 / r2

Where:

• F = Gravitational force
• G = Universal Gravitational Constant
• m₁,m₂​ = Masses of the two objects
• r = Distance between their centers

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🔢 Universal Gravitational Constant (G)

• G = 6.67 × 10⁻¹¹ N m²/kg²
• It is constant throughout the universe 🌠

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🪂 Gravity (g)

• Gravity is the force with which Earth attracts objects towards its center.
• Acceleration due to gravity:

g = 9.8 m/s²

• Value of g decreases with height and depth 🏔️🕳️
• g is slightly higher at poles and lower at equator 🌏

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⚖️ Mass vs Weight

Mass 🧍	Weight ⚖️
Amount of matter	Force of gravity on object
Constant everywhere	Changes with gravity
Unit: kg	Unit: Newton (N)
Scalar quantity	Vector quantity

Formula: W = mg

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🚀 Free Fall

• When an object falls only under the influence of gravity, it is called free fall.
• During free fall, acceleration = g 🌠

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📏 Equations of Motion for Free Fall

Replace “a” with “g”:

• v = u + gt
• s = ut + 1/2gt²
• v² = u² + 2gs

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🌊 Thrust & Pressure

• Thrust: Force acting on a surface.
• Pressure: Thrust per unit area.

Pressure=Thrust / Area

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⚓ Buoyancy & Archimedes’ Principle

• When an object is immersed in a fluid, it experiences an upward force called Buoyant Force ⛵
• Archimedes’ Principle:
  The upward buoyant force is equal to the weight of the fluid displaced by the body.

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🧪 Density and Relative Density

\text{Density} = \frac{\text{Mass}}{\text{Volume}}
]

• Relative Density = Ratio of density of a substance to the density of water.

Let’s Practice!