Class 10 Science Chapter 1: Gravitation notes

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10 Jun, 2025

Class 10 Science Chapter 1: Gravitation notes

Welcome to a complete, in-depth guide on Chapter 1: Gravitation from the Maharashtra State Board Class 10 Science Part 1 textbook. These notes include theory, formulas, derivations, solved examples, differences, and exam-oriented points — perfectly suited for students preparing for SSC Board Exams.

🔹 1. Introduction to Gravitation

Gravitation is the force of attraction between any two bodies in the universe. It is a fundamental force responsible for many natural phenomena like the fall of objects, planetary motion, tides, and satellite orbits.

Board Question: Define gravitation and give two examples. (2 Marks)

🔹 2. Newton's Universal Law of Gravitation

It states that:

"Every object in the universe attracts every other object with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers."

📘 Mathematical Expression:

F = G × (m₁ × m₂) / r²

F: Gravitational Force (N)
G: Universal Gravitational Constant = 6.674 × 10⁻¹¹ Nm²/kg²
m₁, m₂: Masses of two objects
r: Distance between their centers (m)

📘 Important Concept:

If the distance doubles, force becomes one-fourth. If mass doubles, force also doubles.

Expected Question: State and explain Newton’s law of gravitation with mathematical formula. (3 Marks)

🔹 3. Acceleration due to Gravity (g)

It is the acceleration produced in a freely falling object due to Earth’s gravitational pull. Denoted by g.

📘 Formula:

g = G × M / R²

G: Universal gravitational constant
M: Mass of Earth
R: Radius of Earth

On Earth, g = 9.8 m/s²

Derivation: Equating Newton's law and weight,
F = G × (M × m)/R² = m × g ⇒ g = G × M / R²

📘 Variation of g:

With height – g decreases
With depth – g decreases
At poles – g is more
At equator – g is less

🔹 4. Free Fall

When an object falls under gravity alone, it is called free fall. Air resistance is negligible.

Formula: v = u + gt, s = ut + ½gt², v² = u² + 2gs

🔹 5. Mass and Weight

Aspect	Mass	Weight
Definition	Amount of matter	Force of gravity
Unit	Kg	Newton (N)
Quantity Type	Scalar	Vector
Formula	—	W = m × g
Change with Location	No	Yes

🔹 6. Thrust and Pressure

Thrust: Perpendicular force on a surface (N)
Pressure: Force per unit area.
Formula: P = Thrust / Area

Units: Pressure → Pascal (Pa); 1 Pa = 1 N/m²

🔹 7. Archimedes’ Principle

It states that: “When a body is immersed fully or partially in a fluid, it experiences an upward force equal to the weight of fluid displaced.”

Applications: Ships, submarines, hydrometers, etc.

🔹 8. Laws of Floatation

An object will float if:

Weight of object = Buoyant force
Density of object < Density of fluid

🔹 9. Numericals (Sample)

Q: Calculate gravitational force between 10 kg and 5 kg masses placed 2 m apart.

Solution: F = G × m₁ × m₂ / r² = 6.674×10⁻¹¹ × 10 × 5 / 4 = 8.34 × 10⁻¹⁰ N

🔹 10. Important Board Questions (Past 5 Years)

State Newton’s Universal Law of Gravitation and explain it. (2020)
Differentiate between mass and weight. (2019, 2022)
What is free fall? Derive equations of motion under gravity. (2021)
Explain variation of g with altitude. (2023)

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Class 10 Science Chapter 1: Gravitation notes

Class 10 Science Chapter 1: Gravitation notes

🔹 1. Introduction to Gravitation