Why Does Thunder follow Lighting?

During the rainy season we often see lightning in the sky followed by thunder. Do you know what this lightning is and how thunder follows it? In ancient times whenever man saw lightning in the sky and heard thunder he used to believe that gods were angry and punishing him for some sin. Benjamin Franklin was the first person who, in 1872, scientifically explained the occurrence of lightning. In fact, whenever the sky gets overcast with clouds, the small particles of water present in them get charged due to air friction. 

In the process, some clouds become positively charged, while some others negatively charged. When a positively-charged cloud approaches a negatively charged one. There develops a potential difference of millions of volts between them. Because of this high voltage, there is a sudden electric discharge through the air between the two clouds and a streak of light is seen. This is called 'lightning'. The electric discharge through the air produces a large amount of heat due to which the atmospheric air suddenly expands. 

Lighting. 

With this sudden expansion, the innumerable molecules of the air collide with one another producing sound. This is called 'thunder'. Although lightning and thunder are produced simultaneously, yet we see the flash of lightning first. It is so because the velocity of light is very high i.e.,300000 kms.per second. On the other hand velocity of sound is only 332 metres per second. Thus, because of its high velocity, light immediately reaches our eyes, but the sound takes some time to reach our ears.

Whenever a charged cloud passes by some tall tree or high building, by induction, it produces the opposite charge on that tree or building. When the amount of charge so produced is very high, there is a sudden electric discharge in the air. It is then said that lightning has struck such tree or building.

To protect high buildings from such mishaps pointed rods of copper or some other metal are fixed on the top of buildings which passes through them and are buried deep in the earth.

These are called 'lightning conductors'. Whenever some charged cloud passes by such a building and produces opposite charge on it, the charge goes to the earth through the rod and does not damage the building. This is how buildings are protected from the lightning. 

THERE IS A CRACK IN EVERYTHING, THAT'S HOW THE LIGHT GETS IN.

- LEONARD COMEN.

Why is the Tower of Pisa Leaning?

Is the Tower of Pisa Leaning?

Everybody knows that in the city of Pisa in Italy, there is a beautiful tower that "leans" Very ew people know the reason of its leaning Every year thousands of people go there to see the der made of white marble The walls are four meters thick at its base. It has eight story and in 55 meters high. There is a stairway which leads to the top and has 300 steps From as top one can have a magnificent view of the city and the sea which is ten kilometer away.   

Leaning Tower of Pisa, Italy.

Now the question arises: What makes this tower lean and why it does not fall? At the top, the tower is five  meters away from the perpendicular. It leans over by five meters If we drop ball from it's top, a would hit the ground five meters away from its base. It was intended as a bell tower for the cathedral which is nearby. Its construction was started in 1174 and completed in 1350 When the construction started nobody thought that it would lean, but it started leaning after the third story was completed. The foundations of the tower were laid sand and this may explain why it leans. Since the tower started leaning, the plans of its constructs were modified and the tower was completed. During the last one hundred years the tower has leaned another 30 cm.

Now the question arises: Even while leaning, why does it not tall?  According to science anything well remain stable till the vertical line drawn from its center of gravity passes through The center of gravity is that point where the whole of the mass of the body is  supposed to be concentrated. Till today the vertical line from the center of gravity has been falling within the base of the tower. That is why it has not fallen. It is believed that when the tower leans further and the line from its center of gravity pass out of its base, it will fall down According to some engineers the tower will definitely fall one day.  

Rome Wasn't Built In A Day.