F-A-Q's

Sir Issac Newton
Source : scienceworld.wolfram.com

How Did Newton guess the inverse - square rule ?

There has always been a great interest in the motion of planets. By the 16th century, a lot of data on the motion of planets had been collected by many astronomers. It is important to note that Kepler could not give a theory to explain the motion of planets. It was Newton who showed that the cause of the planetary motion is the gravitational force that the Sun exerts on them. Newton used the third law of Kepler which is " The cube of the mean distance of a planet from Sun is proportional to the square of its orbital period T " (To read all the laws of Kepler : http://abslabs.blogspot.in/p/laws.html)
to calculate the gravitational force of attraction. The gravitational force of the earth is weakened by distance.


What is Sonic Boom ?

When the speed of any object exceeds the speed of sound it is said to be travelling at supersonic speed. Bullets, aircraft's etc. often travel at supersonic speeds. When a sound, producing source moves with a speed higher than that of sound, it produces shock waves in air. These shock waves carry a large amount of energy. The air pressure variation  associates with this type of shock waves produces a very sharp and loud sound called the "sonic boom ". The shock waves produced by a supersonic aircraft have enough to shatter glass and even damage buildings.