Understanding Differences Between Gravity and Gravitation
From the motion of celestial planets to the experiences we encounter daily on Earth, the concepts of gravity and gravitation are essential to our understanding of the cosmos. In physics, gravity and gravitation are two distinct phenomena, even though they are closely related and often used interchangeably. This article will discuss the distinctions between gravity and gravitation, along with their definitions, impacts, and relevance in both classical and contemporary physics.
1. Explaining What Gravity and Gravitation Are
It is crucial to define each term precisely before exploring the distinctions between gravity and gravitation.
Gravity: What Is It?
Gravity is the force that draws mass-containing objects together. Specifically, it is the force that controls the motion of celestial bodies like the Earth and the Moon. It also causes objects to fall towards the ground when dropped. Gravity gives physical objects weight, and it causes objects in freefall to accelerate towards Earth. On Earth, gravity is a local force that draws everything towards the centre.
Earth’s gravitational force holds everything, including the atmosphere, the seas, and all living things, firmly to the surface. The gravitational constant, g, which is approximately 9.8 m/s², can be used to describe the strength of gravity on Earth. This value remains constant.
Describe Gravity
The force of attraction between two masses anywhere in the cosmos is called gravity. Unlike gravity, which specifically refers to the Earth’s gravitational pull, gravity is the universal force that governs the interaction of all masses, whether on Earth or in space. Gravity is responsible for the creation of planets, stars, galaxies, and even the overall structure of the universe.
According to Sir Isaac Newton’s law of gravitation, every mass in the universe is drawn to every other mass. The force of attraction is proportional to the product of their masses and inversely proportional to the square of the distance between them. The mathematical expression for this force is:
𝐹 = 𝐺 𝑚₁ 𝑚₂ / 𝑟²
Where:
- The gravitational force between two objects is represented by F.
- The gravitational constant is denoted by G.
- m₁ and m₂ are the respective masses of the objects.
- The separation between the centres of the two masses is denoted by r.
Gravitation, the fundamental force that connects all things in the universe, is distinct from gravity, which is specific to Earth or other large celestial bodies.
2. Important Distinctions Between Gravitation and Gravity
Despite their connection to the force of attraction between objects, gravity and gravitation differ in several key ways, including their origin, scope, and mathematical explanations. Let’s take a closer look at these distinctions.
2.1 Meaning and Extent
Gravity is the force that draws objects towards the centre of a large body, such as Earth. It is a localised phenomenon that is specifically linked to a massive planet, moon, or other celestial body. Gravity determines the weight of objects on Earth’s surface and controls the way things fall, like an apple dropping from a tree or a person jumping into the air. With a gravitational acceleration of around 9.8 m/s², gravity on Earth remains constant.
In contrast, gravitation is the universal force that connects any two mass-containing objects. It affects everything, from tiny objects on Earth to interactions between planets, stars, and galaxies in distant space. Gravity explains the Earth’s orbit around the Sun, the Moon’s orbit around Earth, and the stability of galaxies. Unlike gravity, which is confined to specific celestial bodies, gravitation exists throughout all matter.
2.2 Effect Location
Gravity is the specific gravitational force that acts near a planet or other large mass. It pulls objects towards the centre of that body. For example, the gravitational attraction of Earth pulls everything on its surface towards the centre. Gravity keeps the atmosphere in place, holds water in oceans, and draws roots downward to support plant growth.
However, gravity is not exclusive to any one planet or body. It is the force that attracts all masses to each other, regardless of their distance. This force affects not only Earth and the Moon but also the Sun and the planets, as well as distant stars in other galaxies. The motion of galaxies and celestial bodies in their orbits is also controlled by gravity.
2.3 Formula in Mathematics
Gravity: The formula 𝐹 = 𝑚𝑔, where F is the force attributable to gravity, quantifies gravity on Earth.
- The object’s mass is represented by m.
- The acceleration due to gravity, g, is around 9.8 m/s².
This formula shows that heavier objects experience a greater gravitational pull, which is why gravity gives them weight.
Newton’s law of gravitation states that gravity is calculated using the following formula: 𝐹 = 𝐺 𝑚₁ 𝑚₂ / 𝑟².
This formula shows how the gravitational force depends on:
- The masses of the two objects, m₁ and m₂.
- The separation (r) between the centres of the two objects.
- The gravitational constant, G, is approximately 6.674 × 10⁻¹¹.
Gravitation occurs between any two masses, regardless of their distance from one another, and its intensity decreases with the square of the distance between them (Nm²/kg² / 6.674×10⁻¹¹ Nm²/kg²).
2.4 Power and Impact
Gravity is a force that depends on the mass of the object being attracted and the mass of the Earth (or other celestial bodies). The strength of gravity is affected by the body’s mass and its distance from the centre of the body. The Earth’s surface has a strong enough gravitational pull to keep objects firmly anchored to the ground.
Gravity affects all objects with mass, and it is a universal force. Although gravity is a localised form of gravitation, other fundamental forces, such as electromagnetic force, are much stronger than gravity. Nevertheless, we still feel the pull of gravity over vast distances. For instance, the Earth’s tides and the Moon’s orbit are influenced by the gravitational pull between the two bodies.
2.5 Function in Heavenly Mechanics
Gravity: Satellites, aircraft, and objects in freefall rely on gravity to move when they are close to Earth. Gravity keeps the atmosphere confined to Earth, preventing it from escaping into space. Since gravity governs the most fundamental aspects we encounter daily, such as weight, life on Earth would not exist without it.
Gravitation: Gravitation controls the orbital motion of celestial bodies. It governs the movement of stars within galaxies, the orbits of planets around the Sun, and the Moon’s orbit around Earth. The gravitational interaction between Earth and the Moon causes the tides to rise and fall, while the Sun’s gravity keeps the planets in orbit. Gravitation also explains the behaviour of galaxies and the formation of black holes.
3. Important Lessons Learned: An Overview of the Differences
Gravitation is the universal force that acts between all masses in the universe; gravity specifically refers to the force of attraction between Earth (or other massive bodies) and objects near its surface.
While gravitation acts across vast distances between any two masses in the cosmos, gravity is a localised force that operates within the gravitational field of a planet or other celestial body.
Gravitation governs the structure of the cosmos and the orbits of planets; gravity is also responsible for weight and objects falling to Earth.
The equation F=mg quantifies gravity, while Newton’s law of gravitation, F=Gr², describes gravitation. The formula is 𝐹 = 𝐺 𝑚₁ 𝑚₂ / 𝑟².
