Apply the scientific method to the set of events that led to the discovery of the Universal Law of
Gravitation.
In the beginning of the 16th century, astronomers such as Galileo Galilei and Brahe discovered
that the earth and other planets of the solar system revolved around the earth. Kepler’s laws of
planetary motion showed that the planets moved in elliptical orbits with the Sun as the center
The Universal Law of Gravitation was discovered by Isaac Newton when he saw an apple fall
from a tree. This sparked an interest that led him to question why an apple would fall downwards
from a tree and not remain stationary. The motion of the apple from the tree towards the ground
shows that there is a force of attraction towards the center of the earth in what is termed as
gravity in the modern day
Another event that led to Isaac Newton discovering gravity was when he noticed that the moon
would move away from the Earth in a straight line. The straight line was tangential to its orbit as
if there were force preventing it to fall in a direction towards the earth. This can therefore be
explained that the action of the moon is that of a projectile circling around the earth due to the
action of gravity. The gravitational attraction towards the center of earth is what would cause the
moon to move around the earth without falling.
From the two events Isaac Newton determined that the force between those bodies is gravity and
determined that gravitational forces exist between all objects. Newton was able to determine that
the extent of gravitational attraction was dependent on the distance between them.
Isaac Newton further conducted a study that showed how distance affected the gravitational
force between two bodies. His conclusion was that gravitational force between the Earth and
, other objects is inversely proportional to the distance between the center of the earth and the
center of the object.
Another aspect that determined the force of attraction between two bodies is the mass of the
object. From the event of the falling apple from the tree, the apple’s gravitational acceleration
from the tree towards the earth depended on the mass of the apple and the mass of the earth as
well. He concluded that the apple’s acceleration towards the earth caused the earth’s acceleration
towards the apple hence Newton’s third law
The Universal Law of Gravitation between two bodies can be summarized as an equation as
follows:
M 1M 2
Gravitational Force α
d2
Where M1 is the mass of object 1, M2 is the mass of object 2 and d is the distance between the
objects 1 and 2. The gravitational force is thus directly proportional to the mass of the objects
and inversely proportional to the distance between them. As the mass of the objects increases so
does the gravitational force between them and as the distance between the objects increase, the
gravitational force decreases.
Introducing a constant of proportionality to the equation yields to the equation:
GM 1 M 2
Gravitational force=
d2
The term G is a constant of proportionality known as the universal gravitation constant.
Gravitation.
In the beginning of the 16th century, astronomers such as Galileo Galilei and Brahe discovered
that the earth and other planets of the solar system revolved around the earth. Kepler’s laws of
planetary motion showed that the planets moved in elliptical orbits with the Sun as the center
The Universal Law of Gravitation was discovered by Isaac Newton when he saw an apple fall
from a tree. This sparked an interest that led him to question why an apple would fall downwards
from a tree and not remain stationary. The motion of the apple from the tree towards the ground
shows that there is a force of attraction towards the center of the earth in what is termed as
gravity in the modern day
Another event that led to Isaac Newton discovering gravity was when he noticed that the moon
would move away from the Earth in a straight line. The straight line was tangential to its orbit as
if there were force preventing it to fall in a direction towards the earth. This can therefore be
explained that the action of the moon is that of a projectile circling around the earth due to the
action of gravity. The gravitational attraction towards the center of earth is what would cause the
moon to move around the earth without falling.
From the two events Isaac Newton determined that the force between those bodies is gravity and
determined that gravitational forces exist between all objects. Newton was able to determine that
the extent of gravitational attraction was dependent on the distance between them.
Isaac Newton further conducted a study that showed how distance affected the gravitational
force between two bodies. His conclusion was that gravitational force between the Earth and
, other objects is inversely proportional to the distance between the center of the earth and the
center of the object.
Another aspect that determined the force of attraction between two bodies is the mass of the
object. From the event of the falling apple from the tree, the apple’s gravitational acceleration
from the tree towards the earth depended on the mass of the apple and the mass of the earth as
well. He concluded that the apple’s acceleration towards the earth caused the earth’s acceleration
towards the apple hence Newton’s third law
The Universal Law of Gravitation between two bodies can be summarized as an equation as
follows:
M 1M 2
Gravitational Force α
d2
Where M1 is the mass of object 1, M2 is the mass of object 2 and d is the distance between the
objects 1 and 2. The gravitational force is thus directly proportional to the mass of the objects
and inversely proportional to the distance between them. As the mass of the objects increases so
does the gravitational force between them and as the distance between the objects increase, the
gravitational force decreases.
Introducing a constant of proportionality to the equation yields to the equation:
GM 1 M 2
Gravitational force=
d2
The term G is a constant of proportionality known as the universal gravitation constant.
