Newton was not only a renowned physicist but a famous mathematician too. He was the person who invented the concept of Calculus. The man who explained to the world the concept of gravity through the simple act of an apple falling from a tree on the ground was Sir Isaac Newton.

Newton was inspired by why apples would fall on the ground. This elemental concept gave rise to the concept of gravity, which is the base of all science. **Newton’s law of universal gravitation** was the main revolutionized theory of Newton.

## Newtons – The Alchemist

Sir Isaac Newton, the famous English mathematician, and physicist was born on Christmas day 25th December 1642 in England. Newton through his ideas and inventions became the famous Physicist who significantly influenced the growth of science by laying a strong radical foundation. His concepts and contributions are phenomenal, that even today modern science considers Newton’s theories remarkable.

Some of the best and famous contributions of Newton are Newtonian mechanics, **Newton’s law of universal gravitation**, Newton’s laws of motion, modern physical optics, Calculus, Binomial series, Principia, and Newton’s method.

Newton’s law of universal gravitation states that ** “Every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their center”**. It is symbolically summarised as

Where,

F is the gravity between two objects

m1 is the mass of object 1

m2 is the mass of object 2

d represents the distance between the objects m1 and m2

G is the universal gravitational constant (G = 6.673 x 10-11 N m2/kg2)

Gravity is a universal phenomenon that holds the same. The gravitational force is directly proportional to the mass of objects that interact with each other. Objects with greater mass will attract each other with more gravitational force. When the mass of either object increases, the force of gravitational attraction between them also increases. If the mass of one of the objects is doubled, then the force of gravity between them is doubled, and hence so on.

Now let us know about another famous physicist and mathematician Christian Andreas Doppler.

**The Change Wave Frequency**

Have you heard of the Doppler effect? **Doppler effect** is also known as or Doppler shift is the phenomenon observed when there is a change in frequency of a wave with respect to the observer who is moving relative to the wave source. This concept was explained and put forth by the Physicist and mathematician Christian Andreas Doppler in 1842. Doppler was born on 29th November 1803 in Salzburg.

Doppler Effect can be experienced when an ambulance crosses the observer with its siren blaring.

Doppler effect the key concept of Physics is defined as *“The increase or decrease in the frequency of light, sound, or any other waves as the source and observer move towards or away from each other”.*

The Doppler effect was used to explain the concepts of binary stars. To experience the Doppler effect, the motion of an observer and the source must be along the same straight line.

Doppler effect is used to measure vibrations, hospitals use for medical imaging and to diagnose heart problems, in the measurement of blood flow, calculation of velocity profile measurement, satellite communication, traffic police make use of doppler effect a radar gun to check the speed of the oncoming vehicles.

The doppler effect is represented as

Edwin Hubble used the Doppler effect as one of the evidence to prove that the universe is expanding. Edwin Hubble noticed that the light from distant galaxies was shifted toward lower frequencies, to the red end of the spectrum. Hence we see stars or galaxies in red colour when they are moving away from us.

We can conclude that both Sir Isaac Newton and Christian Andreas Doppler have contributed significantly to the development of Physics and Mathematics. To know more about various inventors and astronomers visit BYJU’S – The Learning App today!!