Gravitation Basics - Easy Physics Guide

Gravitation is the force of attraction between all objects with mass.Every object with mass in the universe attracts every other object.Sir Isaac Newton formulated the law of universal gravitation in the 17th century.The law states that every particle attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them.The mathematical formula is F equals G times m₁ times m₂ divided by r squared.G is the gravitational constant, with a value of approximately six point six seven times ten to the negative eleven newton meters squared per kilogram squared.The force is inversely proportional to the square of the distance. This means that as distance increases, the gravitational force drops dramatically.This fundamental law explains why objects fall to Earth. The Earth's mass creates a gravitational pull on all objects near it.The object falls because of this gravitational attraction, accelerating toward Earth's center.The same law governs how planets orbit the Sun. The Sun's massive gravitational pull keeps planets in their orbits.The balance between the planet's forward motion and the gravitational attraction creates a stable orbit.Newton's Law of Universal Gravitation is truly universal, explaining everything from why objects fall to Earth to how planets orbit the Sun.A gravitational field is a region of space where a mass experiences a force due to the presence of another mass.The gravitational field strength, g, at any point is defined as the force per unit mass.It is measured in newtons per kilogram. Near Earth's surface, g is approximately 9.8 newtons per kilogram.Near Earth's surface, all objects, regardless of their mass, accelerate at approximately 9.8 meters per second squared when falling.This might seem counterintuitive. After all, Earth pulls more strongly on objects with greater mass.The explanation lies in Newton's Second Law. Since force equals mass times acceleration, the mass in the gravitational force equation cancels out with the mass in the acceleration equation.This explains Galileo's famous demonstration that objects of different masses fall at the same rate when air resistance is negligible.As you can see, both objects reach the ground at the same time, despite their different masses.To summarize: a gravitational field is a region where masses experience forces. The field strength is measured in newtons per kilogram. Near Earth's surface, all objects accelerate at 9.8 meters per second squared, regardless of their mass, because the mass in the force equation cancels with the mass in Newton's second law.