Railway Science (Physics-Gravitation)

A fall is considered as a free fall if the only force acting on it was gravity. As the vacuum contains no matter, there is no opposite force against the free fall due to gravity.

Everybody in this universe attracts another body by a force which is called Gravitational force. Centripetal force is the force acting towards the center of the circular path. Centrifugal force acts in a direction pointing away from the center of the circular path. Electromagnetic force: It is a type of force that occurs between electrically charged particles.

Universal law of gravitation: Everybody in the universe attracts every other body with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. Importance - The force that binds us to the earth; The motion of the moon around the earth; The motion of planets around the Sun; The tides due to the moon and the Sun . Universal Gravitational equation: F = G 

Acceleration due to gravity is given as (g) = G × 𝑀/𝑅²
Where, G = Universal constant, M = mass of the planet, R = Radius of the planet. It means Earth's mass 'M' is directly proportional to the gravity, and Earth's radius is inversely proportional to the gravity.

According to Newton's law of gravitation: Everybody in this universe attracts every other body with a force, which is directly proportional to the product of their masses and the inversely proportional to the square of the distance between their centres, i.e., F ∝ 𝑚₁𝑚₂/𝑟².

According to Newton's law of universal gravitation, the gravitational force between two bodies is always attractive. This law states that every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

In the absence of significant air resistance (air friction), objects falling near the surface of the Earth experience the same acceleration due to gravity regardless of their mass. This acceleration is approximately 9.8 m/s² and is directed downwards towards the center of the Earth.

The acceleration due to gravity (g) is stronger closer to the center of the Earth and weaker at higher altitudes. Similarly, the value of ‘g’ decreases with increase of height.

The value of g is independent of the mass of the object and only dependent upon location - the planet the object is on and the distance from the center of that planet. g = 𝐺𝑀/𝑅² where, G is the universal gravitational constant, M is the mass of the planet and R is the radius of the planet.