Search results
slideshare.net
- The laws of gravity describe the trajectories of bodies in the solar system and the motion of objects on Earth, where all bodies experience a downward gravitational force exerted by Earth’s mass, the force experienced as weight.
www.britannica.com/summary/gravity-physics
People also ask
How did Newton calculate the universal law of gravitation?
What is Newton's law of gravitation?
How did Newton explain Kepler's laws?
What is Newton's theory of gravitational force?
Isaac Newton changed the way we understand the Universe. Revered in his own lifetime, he discovered the laws of gravity and motion and invented calculus. He helped to shape our rational world...
- Overview
- Newton’s law of gravity
Newton discovered the relationship between the motion of the Moon and the motion of a body falling freely on Earth. By his dynamical and gravitational theories, he explained Kepler’s laws and established the modern quantitative science of gravitation. Newton assumed the existence of an attractive force between all massive bodies, one that does not require bodily contact and that acts at a distance. By invoking his law of inertia (bodies not acted upon by a force move at constant speed in a straight line), Newton concluded that a force exerted by Earth on the Moon is needed to keep it in a circular motion about Earth rather than moving in a straight line. He realized that this force could be, at long range, the same as the force with which Earth pulls objects on its surface downward. When Newton discovered that the acceleration of the Moon is 1/3,600 smaller than the acceleration at the surface of Earth, he related the number 3,600 to the square of the radius of Earth. He calculated that the circular orbital motion of radius R and period T requires a constant inward acceleration A equal to the product of 4π2 and the ratio of the radius to the square of the time:
The Moon’s orbit has a radius of about 384,000 km (239,000 miles; approximately 60 Earth radii), and its period is 27.3 days (its synodic period, or period measured in terms of lunar phases, is about 29.5 days). Newton found the Moon’s inward acceleration in its orbit to be 0.0027 metre per second per second, the same as (1/60)2 of the acceleration of a falling object at the surface of Earth.
In Newton’s theory every least particle of matter attracts every other particle gravitationally, and on that basis he showed that the attraction of a finite body with spherical symmetry is the same as that of the whole mass at the centre of the body. More generally, the attraction of any body at a sufficiently great distance is equal to that of the whole mass at the centre of mass. He could thus relate the two accelerations, that of the Moon and that of a body falling freely on Earth, to a common interaction, a gravitational force between bodies that diminishes as the inverse square of the distance between them. Thus, if the distance between the bodies is doubled, the force on them is reduced to a fourth of the original.
Newton saw that the gravitational force between bodies must depend on the masses of the bodies. Since a body of mass M experiencing a force F accelerates at a rate F/M, a force of gravity proportional to M would be consistent with Galileo’s observation that all bodies accelerate under gravity toward Earth at the same rate, a fact that Newton also tested experimentally. In Newton’s equation F12 is the magnitude of the gravitational force acting between masses M1 and M2 separated by distance r12. The force equals the product of these masses and of G, a universal constant, divided by the square of the distance.
The constant G is a quantity with the physical dimensions (length)3/(mass)(time)2; its numerical value depends on the physical units of length, mass, and time used. (G is discussed more fully in subsequent sections.)
The force acts in the direction of the line joining the two bodies and so is represented naturally as a vector, F. If r is the vector separation of the bodies, then In this expression the factor r/r3 acts in the direction of r and is numerically equal to 1/r2.
Newton discovered the relationship between the motion of the Moon and the motion of a body falling freely on Earth. By his dynamical and gravitational theories, he explained Kepler’s laws and established the modern quantitative science of gravitation. Newton assumed the existence of an attractive force between all massive bodies, one that does not require bodily contact and that acts at a distance. By invoking his law of inertia (bodies not acted upon by a force move at constant speed in a straight line), Newton concluded that a force exerted by Earth on the Moon is needed to keep it in a circular motion about Earth rather than moving in a straight line. He realized that this force could be, at long range, the same as the force with which Earth pulls objects on its surface downward. When Newton discovered that the acceleration of the Moon is 1/3,600 smaller than the acceleration at the surface of Earth, he related the number 3,600 to the square of the radius of Earth. He calculated that the circular orbital motion of radius R and period T requires a constant inward acceleration A equal to the product of 4π2 and the ratio of the radius to the square of the time:
The Moon’s orbit has a radius of about 384,000 km (239,000 miles; approximately 60 Earth radii), and its period is 27.3 days (its synodic period, or period measured in terms of lunar phases, is about 29.5 days). Newton found the Moon’s inward acceleration in its orbit to be 0.0027 metre per second per second, the same as (1/60)2 of the acceleration of a falling object at the surface of Earth.
In Newton’s theory every least particle of matter attracts every other particle gravitationally, and on that basis he showed that the attraction of a finite body with spherical symmetry is the same as that of the whole mass at the centre of the body. More generally, the attraction of any body at a sufficiently great distance is equal to that of the whole mass at the centre of mass. He could thus relate the two accelerations, that of the Moon and that of a body falling freely on Earth, to a common interaction, a gravitational force between bodies that diminishes as the inverse square of the distance between them. Thus, if the distance between the bodies is doubled, the force on them is reduced to a fourth of the original.
Newton saw that the gravitational force between bodies must depend on the masses of the bodies. Since a body of mass M experiencing a force F accelerates at a rate F/M, a force of gravity proportional to M would be consistent with Galileo’s observation that all bodies accelerate under gravity toward Earth at the same rate, a fact that Newton also tested experimentally. In Newton’s equation F12 is the magnitude of the gravitational force acting between masses M1 and M2 separated by distance r12. The force equals the product of these masses and of G, a universal constant, divided by the square of the distance.
The constant G is a quantity with the physical dimensions (length)3/(mass)(time)2; its numerical value depends on the physical units of length, mass, and time used. (G is discussed more fully in subsequent sections.)
The force acts in the direction of the line joining the two bodies and so is represented naturally as a vector, F. If r is the vector separation of the bodies, then In this expression the factor r/r3 acts in the direction of r and is numerically equal to 1/r2.
Newton's law of universal gravitation says that every particle attracts every other particle in the universe with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
There is a popular story that Newton was sitting under an apple tree, an apple fell on his head, and he suddenly thought of the Universal Law of Gravitation. As in all such legends, this is almost certainly not true in its details, but the story contains elements of what actually happened.
Aug 26, 2024 · Isaac Newton, the brilliant physicist and mathematician, revolutionized our understanding of the universe with his laws of motion and universal gravitation, forever changing the course of scientific inquiry.
Aug 1, 2024 · Newton’s law of gravitation, statement that any particle of matter in the universe attracts any other with a force varying directly as the product of the masses and inversely as the square of the distance between them. Isaac Newton put forward the law in 1687.
Jun 6, 2023 · Sir Isaac Newton invented calculus and explained optics. His most significant work involved forces and the development of a universal law of gravity.
