CBSE Class 9 Science Notes Chapter 9 Gravitation
Gravitation describes the fundamental force that causes objects to attract each other. Sir Isaac Newton introduced the Law of Universal Gravitation to explain this phenomenon. Gravitation is a key force that pulls two bodies toward one another, influencing the movement of celestial objects and objects on Earth.
1.0Gravitation and Gravity
Gravitation-It is the force of attraction that exists between any two objects in the universe.
Gravity specifically refers to the force of attraction between Earth and other material objects. While gravitation is a universal concept, gravity is the localized effect of Earth's gravitational pull.
2.0Newton’s Universal Law of Gravitation
Newton’s Universal Law of Gravitation states that:
- Gravitational force(F) is directly equitable to the product of the masses of two objects (m1 and m2).
- It is inversely equitable to the square of the distance r between their centers.
- The formula for this law is F=Gm1m2r2 where G is the Universal Gravitational Constant, approximately 6.673 ✕ 10-11Nm2Kg-2
- This constant represents the force between two 1 kg masses separated by 1 meter.
3.0Characteristics of Gravitational Force
- Universal Attraction: It acts between all objects with mass.
- Line of Action: It acts along the line joining the centers of the masses.
- Newton’s Third Law: The force is equal and opposite on both objects.
- Inverse Square Law: The force decreases as the distance between objects increases.
- Dependence on Mass: The force increases with greater mass.
- Long Range: It has an effect over long distances.
4.0Importance of The Universal Law of Gravitation
- Anchors to Earth: It keeps us grounded on Earth.
- Planetary Orbits: Explains why planets orbit the Sun.
- Tides: Accounts for tides caused by the Moon and Sun.
Table of Contents
- 1.0Gravitation and Gravity
- 2.0Newton’s Universal Law of Gravitation
- 3.0Characteristics of Gravitational Force
- 4.0Importance of The Universal Law of Gravitation
Frequently Asked Questions
It is the motion of an object solely under the influence of Earth's gravity, without any other forces acting on it.
In free fall, all objects experience the same acceleration due to gravityg, regardless of their mass. Thus, heavier objects do not fall faster than lighter one
The Earth does move towards the Moon, but the Moon's mass is much smaller compared to Earth's, so the Earth's movement is less noticeable.
Earth’s equatorial bulge causes g to be slightly less at the equator and greater at the poles, g varies inversely with Earth's radius, which is larger at the equator.
Acceleration due to gravity g is the specific acceleration experienced by an object in free fall due to Earth's gravity. General acceleration refers to any acceleration caused by forces other than gravity.
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