The universal law of gravity was founded by Sir Isaac newton. According to the universal law of gravitation, every object attracts every other object with a force. Earth attracts all objects towards it. This is due to its gravitational force. Whenever objects fall towards the earth under this force alone, we can say that the objects are in free fall.  The weight of the object on the moon is equal to nearly one-sixth of its weight on the earth. We will also understand thrust and pressure further in the chapter.

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 separation between their centers. It’s called the universal law of gravitational. This law applies to objects anywhere in the universe. Such a law is said to be universal.

When the object falls due to the earth’s gravitational pull, its velocity changes and is said to be accelerated due to the earth’s gravity and it falls freely called free fall. This acceleration is calculated to be 9.8 meters per Second Square.

In the universe, the mass of the object is the same and the weight of the object depends on the acceleration due to the gravity present on earth. So we can say that the mass of the object is the same on the earth whereas on the moon the weight of the object is (1/6) times its weight on the earth.                                  

The force acting on the object perpendicular to the surface is called thrust. And the force that acts per unit area of the object is pressure. The SI unit for the thrust is the newton, and for the pressure is Newton per meter square or Pascal.

In this virtual tour, we will learn about Archimedes’ principles. It states that “A body immersed in a liquid loses weight by an amount equal to the weight of the liquid displaced.” Archimedes’s principle also states that: “When a body is immersed in a liquid, an upward thrust, equal to the weight of the liquid displaced, acts on it.”