Third Law Of Planetary Motion Formula

Also known as the law of harmonies kepler s third law of planetary motion states that the square of the orbital period represented as t of a planet is directly proportional to the cube of the average distance or the semi major axis of the orbit represented as r of a planet from the sun.

Third law of planetary motion formula.

T is the orbital period of the planet. Since mean motion where is the period according to kepler s third law has the same value for all the planets. Orbital velocity formula is used to calculate the orbital velocity of planet with mass m and radius r. The third law is a little different from the other two in that it is a mathematical formula t 2 is proportional to a 3 which relates the distances of the planets from the sun to their orbital periods the time it takes to make one orbit around the sun.

Unlike kepler s first and second laws that describe the motion characteristics of a single planet the third law makes a comparison between the motion characteristics of different planets. The inverse square law is a differential equation. The variable a is the semimajor axis of the planet. So the inverse square law for planetary accelerations applies throughout the entire solar system.

Kepler s third law is generalised after applying newton s law of gravity and laws of motion. P 2 frac 4 pi 2 g m1 m2 a 3 where m1 and m2 are the masses of the orbiting objects. For example in the third volume of the text newton showed that these laws of motion combined with his law of universal gravitation explained kepler s laws of planetary motion. Equation 13 8 gives us the period of a circular orbit of radius r about earth.

2 a radius vector joining any planet to sun sweeps out equal areas in equal intervals of time 3 the square of the period of any planet about the sun is proportional to the cube of the planet s mean distance from the sun. In satellite orbits and energy we derived kepler s third law for the special case of a circular orbit. According to kepler s law of periods the square of the time period of revolution of a planet around the sun in an elliptical orbit is directly proportional to the cube of its semi major axis. Some also describe a fourth law which states that forces add up like vectors that is that forces obey the principle of superposition.

Kepler s third law sometimes referred to as the law of harmonies compares the orbital period and radius of orbit of a planet to those of other planets. Kepler s third law kepler s third law of planetary motion. The squares of the sidereal periods p of the planets are directly proportional to the cubes of their mean distances d from the sun. T 2 a 3.

Using the equations of newton s law of gravitation and laws of motion kepler s third law takes a more general form.