Value Of Acceleration Due To Gravity

There are various concepts and phenomena to be studied in the world. Most people have studied gravity and acceleration in school but understanding the connection between the two and the importance of this phenomenon is confusing for many. This article is going to throw some light on the concept of acceleration due to gravity with the help of meaning and some examples.

What is the value of acceleration due to gravity? Where does the concept of gravity come from?

With the concept of gravitational force given by the great scientist Sir Isaac Newton, he formulated his formulas and concepts. We learned that when a force is applied to an object/body, the force leads to acceleration, which can change the magnitude of velocity or direction of velocity. 

All objects, humans and organisms and even planets are influenced by the gravitational force applied by the earth on them.

It is a well known and observed fact that whenever an object is thrown downward from a height or it is thrown upward, it will eventually fall towards the earth’s surface. This is basically the earth’s gravitational field that attracts these towards its centre.

But suppose this force is applied to a body. In that case, the force must be accelerating the body, so this acceleration of the body under the influence of gravitational force is called gravity or acceleration due to gravity.

Definition: 

Acceleration due to gravity can be defined as the net acceleration on the body due to the virtue of gravitational force by the earth. It acts downwards, that is, towards the centre of the earth and it is also a vector quantity( it has specific direction and magnitude). 

What is the value of gravity acceleration and how is it determined? 

The value of the acceleration due to gravity is mathematically derived from the formula of gravitational force, 

We know gravitational force = {G(universal gravitational constant) into products of mass of body}, whole divided by square of the distance between them. 

But we also know from Newtonian mechanics that force= mass * acceleration. 

Substituting the value of force from the second formula into first, now a= g (substitution)

We get, g = G X mass / d2

Taking in mind various substitutions, we put the mass of earth and radii of earth and the value of universal gravitational constant into the above formulas; we get the value of g as 9.807 m/ s2 

Later on, this value was verified experimentally by various experiments like the time period of a simple pendulum, etc. 

Difference between g and G:

The value of acceleration due to gravity is the physical quantity representing the acceleration the body will face due to the gravitational force. In contrast, the universal gravitational constant is a proportionality constant that was used to make the formula out of the proportionalities between these physical quantities of force, mass and distance that Newton gave.

The value of gravity acceleration is 9.807 m/ s2 and the value of the universal gravitational constant is 6.677 * 10 -11 kg -2 m2.  

These two quantities differ in SI units and also in dimensions. 

The significant difference between the two quantities is that the universal gravitational constant is universal; that is, it does not change anywhere in the universe, whereas the value of g depends on the planets’ radii and therefore it is different for different planets. 

In the case of the earth, the earth’s shape is not a perfect sphere but a geoid. Therefore, the radius is not constant and the value of g changes. 

But on an average value of the equator of the earth, the value is taken as 9.81 and sometimes as 10 for ease of calculation. 

A practical example of the value of g:

1. Let us assume, we are standing on a tall building and we throw a ball (without giving initial velocity) from the terrace towards the ground, the acceleration that the ball will actually face will be g=9.8 metres per second square (assumpted uniform), therefore the velocity and acceleration act in the same direction and therefore the velocity of ball increases. 

We can also find out other results and physical quantities using the standard equations of motion, with consideration of vectors.

2. Let us assume we are standing on the ground and we throw the ball upward. The value of g, instead of acting as acceleration, acts as retardation of 9.8 m per second square because the motion of the ball and acceleration act in opposite directions. 

We can also find out other results and physical quantities using the standard equations of motion, with consideration of vectors.

The value of g changes with the radii of earth and the distance of an object from the earth’s surface/ height of an object, but in calculations we practically assume it to be uniform for ease. 

Conclusion: 

Acceleration due to gravity can be defined as the net acceleration on the body due to the virtue of gravitational force by the earth. It acts downwards towards the earth’s centre and is also a vector quantity( it has a specific direction and magnitude).

The value of gravity acceleration is 9.807 m/ s2. It is not constant and depends on the factors mentioned in the article.