Of course, we now understand that gravity does more than just making things fall. It holds galaxies together, manages the planets’ motion around the Sun, and also defines the structure of the universe itself. We also know that gravity is one of the 4 essential forces of nature, along with electromagnetism, the strong force, and the weak force.
Newton’s Gravity Law states that particles attract each other in the universe using force which is directly proportional to the product of their masses but also inversely proportional to the square of the specific distance between them.
This is a universal physical law derived from the empirical observations by what Isaac Newton referred it as induction. It’s part of classical mechanics and was expressed in the work of Newton.
In the contemporary language, the law states: Each point mass attracts each single other point mass by a specific force directed along the line intersecting the two points. The force is directly proportional to the product of the 2 masses and inversely proportional to the square of the exact distance between them.
The early test of Newton’s law of gravitation between various masses in the laboratory was the conducted during Cavendish experiment by a British scientist called Henry Cavendish in 1798. It was carried out 111 years after the publication of Principia of Newton and nearly 71 years after his death.
Newton’s theory of gravitation looks like Coulomb’s law of electrical forces that is used to determine the magnitude of the electrical force developed between any two charged bodies. They are both inverse-square laws, in which force is inversely proportional to the square of the specific distance between two bodies. Coulomb’s law has the product of two charges substituting the product of the masses, while the electrostatic constant replacing the gravitational constant.
Newton’s theory has since been replaced by Einstein’s theory of universal relativity, but it goes on to be used as the best approximation of the influences of gravity in many applications. Relativity is needed only when there’s a need for high precision, or when dealing with such strong gravitational fields, like those found near very dense and massive objects, or at too close distances (such as the orbit of Mercury around the sun).
The modern law of gravity—Einstein’s universal theory of relativity—is among the most successful theories we’ve. At the same time, we still do not know everything about Newton’s Gravity Law, including the precise way it fits in with other fundamental forces. But here are
8 weighty facts about Newton’s Gravity Law.
1. Gravity keeps our planet (Earth) and the other planets in the solar system in orbit around the Sun. It also holds the Moon in orbit around the Earth.
2. The force of gravity 62 miles (100 kilometers) above Earth is only 3% less than at the surface of the Earth.
3. It is believed that Isaac Newton’s laws of gravity were motivated by observing an apple fall from a tree.
4. Though Newton’s older theory of universal gravitation is precise in many scenarios, modern physics uses Albert Einstein’s universal theory of relativity to define gravity.
4. Gravity can be carried by massless particles known as gravitons.
In the Standard Model, particles often interact with each other through other force-carrying particles. For instance, the photon is a carrier of the electromagnetic force. The theoretical particles for quantum gravity are the gravitons, and great ideas on how they should work from universal relativity are known. Similar to photons, gravitons are perhaps massless. In case they had mass, experiments should’ve shown something—but it does not rule out a ridiculously small mass.
5. Quantum gravity often appears at the lowest length anything can be.
Gravity is so weak, but the nearer two objects are, the stronger it becomes. Eventually, it attains the strength of the other forces at an extremely small distance called the Planck length, mostly smaller than the atom’s nucleus.
6. Gravity creates waves which move at light speed.
Universal relativity predicts the gravitational waves. If you’ve two stars or black holes or white dwarfs locked in common orbit, they slowly get nearer as gravitational waves usually carry energy away. Actually, Earth also produces gravitational waves while it orbits the sun, but the energy loss is very small to notice.
7. Acceleration of objects due to the gravity on Earth is about 9.8 m/s2. If you neglect air resistance (drag), then the velocity of an object falling to Earth rises by nearly 9.8 meters per second each second.
8. Tides are as a result of the Earth rotation and the gravitational effects of the Sun and Moon.