Gravity is the force of attraction between two objects resulting from their mass. Thus it is gravity which continually pulls us towards the earth. Sir Isaac Newton came to the conclusion that gravitational force exists between all bodies. Thus, two stones are not only individually attracted towards the earth but also attract each other. Normally, we do not notice this force owing to its smallness, although it can be measured with sensitive instruments. Nevertheless, two 50000 ton ships lying side by side attract each other with a force of about 40 lb. wt. Newton's law of universal gravitation states that any two pieces of matter attract one another with a force which is proportional to the product of their masses and inversely proportional to the square of their distance apart. Newton realised that gravitational attraction applied not only to bodies on the earth but was also responsible for holding the planets in their orbits round the sun. Research Gravity
Abbreviations
SciTech
Research Gravity