# Gravitation

## What is the Gravitational Force?

This universe has a lot of forces, pushes, and pulls. We are always pulling or pushing something, even if only the ground. However, it turns out in physics; there are only four fundamental forces in real from which everything else is derived, whether the strong force, the weak force, the gravitational force or even the electromagnetic force as well.

The gravitational force is that which attracts any two objects with mass. We call this force attractive because it always tries to pull the masses together, but it never pushes them apart. In fact, every object, including we (a human body), is pulling on every other object in this entire universe! This is simply nothing but Newton's Universal Law of Gravitation. Admittedly, we don't have a huge mass, and so, we're not pulling much on those other objects. Moreover, objects that are really far apart from each other do not either pull on each other noticeably. Nevertheless, there is the force, and we can calculate it.

### Newton's Universal Law of Gravitation

The Gravitational Force or Newton Gravity or even the gravitational force between two objects Fg is always attractive and depends only on the distance and the masses involved between them. Every object present in the universe attracts every other object with force on a line joining them.

The equation for Newton gravity is given by,

Fg =  $\frac{Gm_1m_2}{r^2}$

Where G refers to the gravitational constant, equal to 6.67 × 10-11 $\frac{m^3}{kg.s^2}$, and

Fg is the gravitational force between m1 and m2, and m1 and m2 are the masses.

The equation given above is also referred to as the gravitational force between two objects.

The force or newton gravity is inversely proportional to the square of the distance between their centers of mass and directly proportional to their masses' product. This is known as inverse-square law.

For example, if we double the distance between the Moon and the Earth, the attractive force between the both of them would go down (since it is inverse), and it would go down with a factor of 4 instead of 2, because of the square.

It describes that both objects falling down and those in a circular orbit, like a satellite around Earth.

### Types of Gravity

Isaac Newton has discovered gravity. He identified it when he saw a grapefruit falling from a tree, and then he started wondering the forces of the universe. It is the force; one attracts a body toward the center of the Earth.

A few of the types of gravity has given below by describing each of them.

Artificial Gravity

Artificial Gravity is the hypothetical expansion or reduction of apparent gravity (for example, force). Mostly, this is used in space and also on earth, which is called Earth gravity. This can be attained by using various forces. For instance, the linear acceleration and the centripetal force.

Microgravity

This is the pressure that is parallel to the surface within the region of phase displacement, whereas, in the universe, it acts on a displaced void. This gravity is that it pushes things into black holes.

Quantum Gravity

The most primitive form of gravity is enfolding the surface tension. This is the actual gravitational field of a black hole and can be referred to as brane gravity since it defines a surface with no intrinsic volume or depth.

Specific Gravity

This is the contracting pressure of masses, which are parallel to the surface within the boundaries of the surface gravity. This begins at the lowest boundary of surface gravity (for example, the Mantle of Earth).

Weak Cosmic Gravity

This is really a cosmic spacetime density function. The geodesic effects define mass for weak bosons because of the ambiguous partial interactions applied to the singularity-horizon bubbles. These field bubbles are overlapping and uncountable. Their interaction forms the cosmological constant and omega modifiers of mass squeezing 417 trillion light year potential into 46.85 Gly.

### The Gravitational Force of Moon on Earth

The acceleration due to the Moon gravity surface is about 1.625 m/s2 and in turn, about 16.6% that on Earth's surface or 0.166 ɡ. Across the entire surface, the gravitational acceleration variation is about 0.0253 m/s2, which is 1.6% of the acceleration due to gravity. Because weight is always directly dependent upon the gravitational acceleration, particles on the Moon will weigh only 16.6% (≈ 1/6) of what they weigh on the Earth, in fact.

### Characteristics of Gravitational Forces

The main characteristics of Gravitational Forces can be given as,

• Basically, the gravitational force is a central force that works across the line joining the centers of two bodies.

• This force is always a long-range force. The force occurs even when we are talking about a considerable distance.

• It is also a conservative force. This implies the work done by the gravitational force in displacing a body from one point to another and is only dependent on the initial and final positions of the body. Also, it is independent of the path followed.

• It is essential to know that unlike electrostatic and magnetic forces, the gravitational force is always attractive.

1. Explain the Gravitational Anomalies?

Ans. Gravitational anomalies are the differences between the observed acceleration of gravity, or free-fall, on a planet's surface. The corresponding value is predicted from a model of the gravity field of the planet. The model is typically based on simplifying assumptions, like that, under its rotational and self-gravitation motion, the planet assumes the ellipsoid figure of revolution. Then, the surface gravity of this reference ellipsoid is given by a simple formula that contains only the latitude and subtraction from observed gravity in the same location yielding the gravity anomaly.

2. Mention the typical example of Gravitational Force in our daily life?

Ans. Gravity is the force that pulls anything down to the centre of the Earth. There will be countless examples of gravitational forces. Let us look at some of them down below.

• Our weight - If there were no gravity, we would weigh nothing

• An apple falling from a tree - The reason how Issac Newton discovered gravity

• Kicking a football up in the air, obviously, it comes back down

• Buildings sticking to the ground

• Jumping up and down

• Rain falling from the sky due to gravity

• All planets forming the solar system - Why the planets are orbiting the Sun is due to its substantial gravitational pull

• Waves in the sea are mostly formed because of the gravity of the Moon

• The Milky Way galaxy is spinning because of the enormous gravitational pull of the supermassive black hole in the very centre (which is 4 million times to the mass of the Sun).