This chapter explains the force of gravitation, which is the force of attraction between any two objects having mass. It describes how gravitation governs the motion of planets, moons, and satellites, and also affects objects on Earth. The chapter introduces Newton’s universal law of gravitation and explains how the same force causes objects to fall towards the Earth. It further discusses important concepts such as acceleration due to gravity, mass, weight, free fall, and thrust and pressure. The chapter also explains why objects float or sink in liquids using Archimedes’ principle, helping students connect gravitation with everyday experiences.
Key Points
Gravitation is the force of attraction between any two masses in the universe.
Every object in the universe attracts every other object.
Newton’s universal law of gravitation states that the force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
The gravitational force keeps planets in their orbits around the Sun.
Objects fall towards the Earth due to its gravitational pull.
Acceleration due to gravity (g) is the acceleration of an object falling freely under gravity.
The value of g on Earth is approximately 9.8 m/s².
Free fall is the motion of an object under the influence of gravity alone.
Mass is the amount of matter in an object and remains constant everywhere.
Weight is the force with which an object is attracted by the Earth and depends on gravity.
Weight changes with location, but mass does not.
Thrust is the force acting perpendicular to a surface.
Pressure is thrust per unit area.
Pressure in liquids increases with depth.
Archimedes’ principle explains the buoyant force acting on objects in fluids.
Objects float or sink depending on their density compared to the liquid.
Buoyancy is the upward force exerted by a fluid on an immersed object.
👉 👉Gravitation shows that natural laws govern both the universe and everyday life. By understanding gravity, we learn why objects fall, why planets move in fixed paths, and how forces shape our world. This knowledge helps us apply science thoughtfully, from simple activities to advanced technologies like satellites and space exploration.