# Kepler’s laws of Planetary Motion for CBSE Class 11th

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Kepler's law of planetary motion

CBSE Class 11th

By iProf

Johannes Kepler

Johannes Kepler was a German mathematician, astronomer, and

astrologer. A key figure in the 17th century scientific revolution, he is best

known for his laws of planetary motion, based on his works Astronomia

nova, Harmonices Mundi, and Epitome of Copernican Astronomy. These

works also provided one of the foundations for Isaac Newton's theory of

universal gravitation.

Keplers's law of planetary motion

In astronomy, Kepler's laws of planetary motion are three scientific laws

describing the motion of planets around the Sun. Kepler's laws are now

traditionally enumerated in this way.

Three laws of Kepler

1

Kepler's first law- Law of orbit

Kepler's second law- Law of equal areas

2

Kepler's third law- Law of periods

3

Kepler's first law- Law of orbit

Every planet revolves in an elliptical orbit around the sun. The orbit of every

planet is an ellipse with the Sun at one of the two foci.

Kepler's second law- Law of equal area

A line joining a planet and the Sun sweeps out equal areas during equal

intervals of time.This law is known as Kepler's second law.

Kepler's third law- Law of periods

The square of the orbital period of a planet is directly proportional to the cube

of the semi-major axis of its orbit.

According to Kepler's third law :P2/a3

Mathematical representation of Kepler's third law

P2/a3

`P' is the time taken for a planet to complete an orbit around the

sun

`a' is the mean value between the maximum and minimum

distances between the planet and sun

Contribution of Kepler's law

With the help of Kepler's second law, Newton introduced the Law of

universal gravitation (Newton's law of gravitation).

Kepler's laws are very useful in the study of planet orbit systems.

These laws are also very important for satellite motion.

Newton's law of universal gravitation

Newton's law of universal gravitation states that any two bodies in the universe attract

each other with a force that is directly proportional to the product of their masses and

inversely proportional to the square of the distance between them.

m

M

r

Mass of body 1

Universal gravitational

F= GmM

constant

r2

Distance between

Mass of body 2

two matter

CBSE Class 11th

By iProf

Johannes Kepler

Johannes Kepler was a German mathematician, astronomer, and

astrologer. A key figure in the 17th century scientific revolution, he is best

known for his laws of planetary motion, based on his works Astronomia

nova, Harmonices Mundi, and Epitome of Copernican Astronomy. These

works also provided one of the foundations for Isaac Newton's theory of

universal gravitation.

Keplers's law of planetary motion

In astronomy, Kepler's laws of planetary motion are three scientific laws

describing the motion of planets around the Sun. Kepler's laws are now

traditionally enumerated in this way.

Three laws of Kepler

1

Kepler's first law- Law of orbit

Kepler's second law- Law of equal areas

2

Kepler's third law- Law of periods

3

Kepler's first law- Law of orbit

Every planet revolves in an elliptical orbit around the sun. The orbit of every

planet is an ellipse with the Sun at one of the two foci.

Kepler's second law- Law of equal area

A line joining a planet and the Sun sweeps out equal areas during equal

intervals of time.This law is known as Kepler's second law.

Kepler's third law- Law of periods

The square of the orbital period of a planet is directly proportional to the cube

of the semi-major axis of its orbit.

According to Kepler's third law :P2/a3

Mathematical representation of Kepler's third law

P2/a3

`P' is the time taken for a planet to complete an orbit around the

sun

`a' is the mean value between the maximum and minimum

distances between the planet and sun

Contribution of Kepler's law

With the help of Kepler's second law, Newton introduced the Law of

universal gravitation (Newton's law of gravitation).

Kepler's laws are very useful in the study of planet orbit systems.

These laws are also very important for satellite motion.

Newton's law of universal gravitation

Newton's law of universal gravitation states that any two bodies in the universe attract

each other with a force that is directly proportional to the product of their masses and

inversely proportional to the square of the distance between them.

m

M

r

Mass of body 1

Universal gravitational

F= GmM

constant

r2

Distance between

Mass of body 2

two matter