Gravity and Gravitational force have often been used interchangeably and to be very honest, most contexts can allow this swap. But to be speaking technically, there is a fine line between both the concepts and their principles. Sir Isaac Newton AND your physics teacher will be majorly disappointed if you’d be confused between them and we really need that A grade on that unit test, don't we? :)
So be a darling and read further as to how these two terms differ in their concepts!
Gravitational Force vs. Gravity
The main difference between gravitational force and gravity lies in their definition and involvement of masses. Gravitational force is a concept that is applied when at least 2 or more objects are involved whereas the concept of gravity can be applied to any object that lies in any geographic location possessing gravity.
Difference Between Gravitational Force and Gravity in Tabular Form
|Parameters of Comparison||Gravitational Force||Gravity|
|Definition||Force exerted by any body having physical mass on every other body.||A force that attracts any body with physical mass towards the center of the earth.|
|Range||The gravitational force is considered to exist for any two objects in the whole cosmos.||Gravity is subjective to the certain celestial body and exists on that body and within a certain range of proximity level around it.|
|Description||The gravitational force can be considered a universal force.||Gravity is not a universal force.|
|Nature||The gravitational force can either be an attractive force or a repulsive force.||Gravity is always an attractive force.|
|Strength||The gravitational force is comparably weaker.||Gravity is comparably stronger.|
|Mass requirement||The gravitational force needs at least two objects having physical masses to exist and be explicable.||Gravity can exert force upon independent objects and thus, needs only a single object having physical mass.|
|Direction||The gravitational force between two masses is directed away from them in a radical direction.||Gravity always pulls the body toward earth, along the line that exists between the center of the body and the center of the earth.|
|Zero-force phenomena||The gravitational force between any two masses is considered nil when the distance between the bodies is infinity.||Gravity is considered nil when the body is said to be at the center of the earth.|
|Example||Revolution of celestial bodies such as the moon around the earth.||Water flowing from the ground at a higher level to the ground at a lower level.|
What is Gravitational Force?
Gravitational force, otherwise referred to as the result of Gravitation, is the force that any body or object having physical mass exerts on every other object. Gravitational force is considered a universal force since it exists throughout the cosmos, regardless of geographic location. There are said to be exactly four fundamental forces in nature that govern the interaction of real-life objects and they are: Strong, Weak, Electromagnetic, and gravitational. Albeit considered the weakest of them all, Gravitational force holds the utmost importance when viewing the big picture. It is this exact phenomenon that helps keep the universe together as it is and not collapse. How does this work exactly?
Holding The World Together!
Gravitational force is exerted by any body having physical mass and this applies to celestial bodies too. The strength of this force depends upon the two masses between which the force is being calculated. This is why smaller masses show no difference despite the existence of gravitational force. Since celestial bodies have enormous masses, there is a high amount of gravitational pull too. In this case, the solar system must've been a game of pool with bodies colliding into each other, but why does this not happen?
When a celestial body, such as earth, is moving around the sun, it moves with a certain velocity and direction. Along with this, there is a certain gravitational force between the sun and the earth, pulling the earth towards the sun. However, the velocity of the earth is directed perpendicular to that of the gravitational pull. Due to the overlapping of both these phenomena, the earth moves in an almost-circular motion around the sun, providing it its elliptical orbit. Thus, the earth does not collide or fall into the sun and remains orbiting around the sun.
This can be applied to other celestial bodies revolving around each other for centuries, such as the moon around the earth. This force is also why Saturn has rings made up of rocks and ice that keep orbiting at certain velocities.
Pulling The Roots: History and Origins
Around 1687, Sir Isaac Newton contributed all the more to the discovery of gravitational effects by establishing “The Universal Law of Gravitation”. He stated that the gravitational pull between two objects is always proportional to the product of the masses of the two objects and inversely proportional to the distance between them. This can mathematically be represented as
Where, m1= mass of the first object
m2= mass of the second object
r= distance between the two objects
F= Gravitational force between two objects
G= Gravitational constant that can be applied throughout the universe
It can also be given by the value G= 6.67× 10-11
Thus, we can draw easy inferences form the formula that:
- Higher the distance between the two bodies considered, lesser the force of attraction between them. Thus there is a chance of the zero-force effect.
- Larger the masses, the higher the force of attraction between them.
Examples of Gravitational Force at Play:-
- Tides in water bodies: These are caused due to the gravitational pull of the moon exerted on the earth. This is why the tides are said to be higher when the moon looms closer to the earth.
- Gasses in the sun: Gravitational force holds all the gasses in the sun and does not let them leave its surface.
- Saturn’s rings: Gravitational force is the reason that the rings around Saturn, made of ice and rocks, revolve in a fixed orbit around the celestial body without drifting apart, similar to other revolution examples of celestial bodies
What is Gravity?
Gravity can exist on other celestial bodies. However, it is not the same on every planet and keeps differing from one another. Owing to this fact, gravity cannot be considered a universal force. However, through this article, we shall talk about gravity in terms of the earth for convenience.
Gravity can be described as the force that pulls every body having some physical mass towards the center of the earth. This pull is directed toward the earth, in a line that stretches from the center of the object to the center of the earth. Any item thrown into the air will fall back on the earth along this line. But how was this established?
Elements of Gravity:-
When a body or an object having significant physical mass is suspended in air, it is bound to fall back with some acceleration. This value of acceleration is known as acceleration due to gravity and stands at a certain value when on earth’s surface at sea level. It is represented by ‘g’ and given by
This is the value that differs in every celestial body and defines the strength of gravity in that certain geography.
This gravity exerts a certain force on everybody, it is represented by Fgand given by-
Where m= mass of the object
g= acceleration due to gravity
There are specific factors that affect the value of ‘g’:
- Shape of the earth: The earth is not said to be a perfect sphere. It has a higher radius at the equator when compared to that at the poles. Since the value of ‘g’ is inversely proportional to the radius of the earth, ‘g’ will be higher at the poles and lower in the equatorial regions.
- The rotation of the earth: Due to the centrifugal force, there is a higher value of ‘g’ at the poles when compared to that at the equator.
- Height over the earth’s surface: The value of ‘g’ is inversely proportional to the height of the object above sea level. That can be formulated by,
- Depth under the earth’s surface: The value of ‘g’ is inversely proportional to the depth of the object below the surface of the earth. This is formulated as
Discovering the Gravitas of Gravity!
The story of gravity and how it was discovered is anything but new information. Although Newton discovered and contributed to science in more than one way towards light, motion, math, and many more, the most famous one of them all is the historical fall of the apple in 1666 which led Newton to wonder what pulls all the objects towards the earth. The discovery of gravity led to the formulation of the universal law of gravitation and thus, the gravitational force.
Gravity is said to have the strength to bend light. Black holes are said to have such strong intensity of gravity that even light cannot escape the suction, earning it its name.
Here are some examples of that reason why gravity defines our life the way it is:-
- Stability: objects remain stable when there is no external force acting on them because gravity acts on them. They do not float or levitate as they’d in space.
- Natural phenomena such as waterfalls: Waterfalls are one of the enormous number of examples that represent gravity and construct nature in one or more ways. Water flows from higher ground to lower ground. This also gave rise to the invention of hydroelectricity.
- Rolling: It is not just water that benefits from the effects of gravity. Objects, both living and nonliving, roll down slant surfaces. There need not be any need for suspension-and-drop for gravity to act upon any object. Even slant surfaces allow objects to roll and fall(incoming flashbacks from horrible trekking trips:) )
- Precipitation: Another major, major contribution of gravity is precipitation. This could be snow, rain, hail, etc. Without a critical part of the life cycle, there’ll possibly be no life on earth. Another beautiful element of gravity!
Main Differences Between Gravitational Force and Gravity in Points
- Any body with physical mass exerts a force on other objects with physical mass. This force is known as the gravitational force. On the other hand, Gravity is the force that attracts the body possessing physical mass towards the center of the earth.
- Gravitational force exists between any two bodies in the universe whereas gravity exists differently in each celestial body. It exists on the specific body and within significant proximity around it. Thus, gravity is subjective to the geographic location of consideration.
- Thus, Gravitational force is considered a universal force whereas gravity cannot be considered a universal force.
- Gravitational force can be both an attractive force or a repulsive force but gravity can only be an attractive force.
- This Gravitational force is always directed in a direction away from the masses. Gravity is always directed towards the earth and the attraction is considered along a line drawn between the earth and the body having physical mass.
- Although it differs from one celestial body to another, it is considered the stronger of the two when compared to gravitational force.
- Gravitational force exists between any two objects and thus requires at least two bodies with physical masses. Gravity, however, works on independent objects. Thus, it does need any set of objects and exerts a force on all objects within the radius.
- The zero-force effect occurs when the said phenomena have zero force or effect in certain conditions. It occurs with gravitational force when the two considered objects are placed at an infinite distance from each other. On the other hand, Gravity is said to exert zero force on any object when it is said to be at the center of the earth when talking in the context of gravity on earth.
- A very common and popular example to explain the phenomenon of Gravitational force is the revolution of planets around the sun. An example to explain gravity is when water flows from higher grounds to lower grounds.
To summarize this discussion, we can say that gravity exists on every object independently whereas gravitational force is calculated between any two objects. Gravitational force exists universally, no matter how small, whereas gravity exists within a certain range for a certain value.
Now go to that test! :)