# Is Gravitational Force A Contact Force: Why, How, When and Detailed Facts

In this article, we are going to discuss is gravitational force a contact force or a non-contact, why is gravity a non contact force, the reasons, and some facts.

A gravitational force is a force of attraction exerted by two bodies on each other and is a non-contact force between the two objects.

## What is a Gravitational Force

The gravitational force is one of the four fundamental forces in nature and is the weakest force of attraction than the electromagnetic force, strong force, and weak force.

The gravitational force is a force of attraction between the two bodies having mass and separated by a distance ‘r’. The gravitational force is known to be an attractive force because it is exerted equally and opposite by the two objects on each other that keeps them binding in an orbit. Such that objects with less mass will tend to orbit around the heavier body, while both the objects with equal masses will revolve in the same orbit with respect to each other.

The idea of gravitational force was thought of first by the famous scientist Newton and he stated the law of gravity which says that “The gravitational force between the two bodies is proportional to the product of the two masses and inversely proportional to the square of the distance between them”. It is formulated as

F=G*(m1m2)/r2

Where G is a gravitational constant G=6.67*10-11

R is the distance of separation between two objects with mass

The same is illustrated for point charges in the electric field. The electric force experienced by two point charges q1 and q2 separated by a distance ‘r’ is given by

Where

is a Coulomb’s constant.

## Characteristics of the Gravitational Force

• It is the weakest force of all the fundamental forces in nature.
• It is an attractive force held between two bodies that keep them bounded with each other.
• It is a non-contact force that is exerted on the body from the distance separated from each other.
• No field is required for two bodies to exert force on each other.
• It is a long-range force. For example, the moon orbiting around the Earth is due to the gravitational pull of the Earth, the planets revolving around the Sun, the high tides and low tides on the Earth due to the gravitational pull of the Moon on the Earth.
• The gravitational force depends upon the masses of the two object exerting force on each other.
• The gravitational force decrease to the square times the length separating the objects as the distance between them increases.
• The gravitation constant ‘G’ value is constant on the Earth.

## Why is Gravity a Non-Contact Force

In Latin, gravity means ‘weight’. The gravitational force exerted on every object surrounding the Earth is known as gravity.

Have you ever wondered if there was no gravity of the Earth then what would have happened? We would have just floated in the air, not able to walk on the surface. The Earth in the orbit would have revolved at a faster rate around the Sun, all the objects would have just freely drifted in the atmosphere, we would have not been able to drive any vehicles, and trees would have not grown on the ground and so many things…

The world is as it is, is only because of the Earth’s gravity, this solar system exists only because the gravitational attraction exerted by the Sun is far stronger than any other object in this system.

The force exerted by the Earth on the objects surrounding it is due to the Earth’s gravitation force and the same is formulated as given below:

Where G is a gravitational constant

ME is the mass of the Earth

M is a mass of the object

RE is the radius of the Earth

h is an altitude above the surface of the Earth, if the object is on the surface of the Earth then h = 0.

If the object is present at infinity then it is concluded from the above expression that the force vanishes at the largest distance.

According to Newton’s Second Law of motion, “The acceleration of the object depends upon the net force acting on it and the mass of the object, the acceleration of the body is directly proportional to the force acting on it and inversely proportional to the mass of the object” and is represented as F=ma. The greater the mass of the object, the less is its acceleration.

Comparing the equation of gravity due to earth and Newton’s 2nd law of motion, we have

‘g’ is an acceleration due to the gravity of the Earth and it is constant on the Earth except at the magnetic poles of the Earth because the magnetic strength of the Earth is higher at the pole hence the ‘g’ value is slightly increased to 10m/s2.

Due to gravity, the weight of any object on the planet Earth will be mass times the acceleration due to gravity (Weight=Mass´g). The work done by the gravitational pull of the Earth on the object is

Work done = mgh.

The work done is equal to the potential energy of an object at a certain height ‘h’ from the ground.

Gravity is said to be a non-contact force because the gravitational force is exerted by one mass on another from the distance separated between them and without being in physical contact. All the objects having mass are bounded to one another by the gravitational pull of attraction. Gravity is a central force because it is directed towards the center of the objects.

## How Gravitational Force is Non-Contact Force

All the objects with masses show some gravitational force which varies with respect to the distance of separation between two objects into consideration joint by a single line. The force experienced by both the objects on one another is the same.

Have you ever noticed when the ball is thrown in the air, it will stop accelerating for very finite milli-seconds when it is reached at its highest peak and then the speed of the ball will exponentially increase until it bounces the ground? At the peak, the ball gains the potential energy and is gradually converted into kinetic energy and a ball accelerates at faster rates, because the gravitational force on the ball increases with decreasing distance. The distance covered by the ball while approaching the ground is a square time of the distance elapsed by it.

Well, the gravitational force is a force between the Earth and the ball, the force exerted by each are equal in magnitude and acts in an opposite direction. Farthest the body, less is the gravitational force experienced on each other.

## Unit of Gravitational force

The unit of gravitational force is Newton, named after the scientist Isaac Newton for his discovery.

The universal gravitational constant G has a value 6.67*10-11 N.m2/kg2. Substituting this in a gravitational force formula in CGS unit we gets

Hence, the unit of the gravitational force is Newton.

## What is the gravitational force between the Earth and the Sun?

Because of the presence of the gravitational pull between the Earth and the Sun, the Earth revolves in an orbit around the Sun.

We know:

The mass of the Earth ME= 6*1024

The mass of the Sun Ms= 2*1030

The distance between the Earth and the Sun d= 1.5*1011

The gravitational constant G = 6.67*10-11

Therefore,

The gravitational force between the Sun and the Earth is approximately

## What is the gravitational force between the Sun and Jupiter?

Planet Jupiter is the largest juvenile planet in our solar system and it pulls all the terrestrial bodies approaching our planet Earth.

The mass of the Jupiter M= 1.9*1027 kg

The mass of the Sun Ms= 2*1030 kg

The distance between the Sun and Jupiter is d = 7.8*1011 m.

Therefore, the gravitational force between the Sun and the Earth is approximately 42*1022

The gravitation force between the Sun and Jupiter is more than the gravitation force between the Earth and the Sun is because the mass of the planet Jupiter is much greater than that of the Earth.

## How are the satellites launched in space?

The satellites are launched into space on rockets with tons of propellant to produce enough trust to boost away from the Earth’s atmosphere.

Once the rocket reaches a particular distance in space, from where there are no chances of a satellite falling back into the Earth’s atmosphere or returning back on the Earth, the rocket will release the satellite into the space or an orbit of any planet on which the studies are to be carried out. The satellite takes the momentum from the rocket to enter the orbit of the planet. The gravity of the planets attracts the satellite towards it while the momentum of the satellite acts perpendicular to the direction of the gravity which keeps the satellite in motion and revolves around the planets in an orbit.