Tides

What causes tides?

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Swing Bowling

 HOW DOES A BALL SWING IN AIR??

In a cricket-frenzy country like India, cricket lives in almost every street of the country. Every fast bowler wishes to master swing bowling, and would love to see his delivery baffling the batsman. Ever wondered how swing bowling actually occurs? How is it that the ball just swirls around in the air as if it is magically controlled by the bowler? What are the techniques followed?

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Nuclear Bombs

On 6 August, 1945 the city of Hiroshima in Japan experienced the horrors of nuclear warfare for the first time in the history of the world. And 3 days later on August 9, the city of Nagasaki was razed to the ground by yet another nuclear bomb. The bombings brought Japan to its knees and ended the Second World War

                          

 Since then the world has been living in constant fear of destruction. The nuclear bomb has been called the most destructive weapon to have ever been made by mankind. From a scientist’s perspective it is an extremely interesting study. What immediately comes into our mind when we think of an atom bomb (as it is popularly called)? We think of a huge mushroom cloud forming over the site of explosion. Why does this mushroom cloud form? What makes these bombs so destructive? These are some of the many questions that have to be answered.

A nuclear weapon is a destructive weapon that derives energy from a thermonuclear reaction. It uses the energy taken from the nuclei of atoms and transforms it to incredible amounts of heat and light. There are two main types of nuclear bombs, namely nuclear fission bombs and nuclear fusion bombs. Nuclear fission bombs were the types of bombs dropped on the Japanese cities of Hiroshima and Nagasaki. The nuclear fusion bombs were developed much later and are much more powerful than fission bombs. These have never been used in warfare. It is said that one fusion bomb is equivalent in destructive capacity to around 700 fission bombs. The fusion bombs are also called hydrogen bombs.

Though both the fusion and fission bombs are called nuclear bombs, they both follow two different processes. The nuclear fission bombs are based on the principle of (no prizes for guessing ;-) nuclear fission while the fusion bombs use the principle of nuclear fusion.

Fission is the process of splitting up of a large nucleus into two or more smaller nuclei on the impact of an energetic neutron. This is accompanied by the release of extremely high amounts of energy. Generally a uranium nucleus is used in fission bombs. When the nucleus is bombarded by a neutron, it breaks into two nuclei, one Krypton and one Barium nucleus along with the release of three more neutrons. Each neutron in turn splits up a uranium atom. This results in an uncontrolled chain reaction culminating in a catastrophic explosion.

Nuclear fusion on the other hand involves the fusing of a deuterium nucleus and a tritium nucleus  to give a helium nucleus accompanied by a free neutron. This releases a much higher amount of energy than nuclear fission. But nuclear fusion is much tougher to attain on earth because the activation temperature for this reaction can only be attained by means of a nuclear fission reaction. The sun releases all its energy due to nuclear fusion reactions of hydrogen to form helium.

Now, we come to the question of the mushroom cloud, the worldwide symbol of horror connected to the nuclear bomb. Why does this mushroom cloud form?

                When the bomb detonates at ground level, the surrounding areas of up to 3 kilometre radius are vaporised due to the heat of explosion. The resulting hot gases and debris become lighter than the surrounding air and rise up at an extremely high speed . This forms the stem of the mushroom. Then as the speed of the hot gases slows down, they expand outward slowly thus giving rise to the shape of a mushroom. The mushroom head stops expanding when it reaches a height where its density is equal to the density of the surrounding air.                                        

On a historical note, nuclear bombs were an important factor in escalating tensions between the United States of America and the USSR during the Cold War. Both the countries constantly threatened to “display” their nuclear power to the other country, throwing the whole world into confusion, because if there is any sure shot method to destroy all human civilisations on the Earth, nuclear war is the way. Presently all countries are following processes of decreasing their nuclear arsenal.

Why am i saying that a nuclear war will destroy the world? Experts have conducted extensive research and found out what will happen in case of a nuclear war. If a sufficiently large amount of nuclear bombs (around 50) are detonated around the world, the huge fires following the nuclear explosions will lift enormous amounts of ash into the atmosphere. This will block most of the sunlight from reaching the earth’s surface and thus kill all the plants which are dependent on sunlight for their daily food. When all the plants die, the whole ecosystem collapses because all animals directly or indirectly depend on plants for sustenance. The global temperatures will drop, plunging the earth’s fragile ecosystem into another ice age. Millions of people will die from the explosions themselves and the unlucky ones who survive will have to bear the horrible effects of radiation.  “And the living prayed for death “. This will be the situation in case of a nuclear war. Thus we can see that nuclear weaponry is an extremely dangerous tool and has to be governed responsibly. After all

WITH GREAT POWER COMES GREAT RESPONSIBILITY!!!

BY

BHARAT, NSS VOLUNTEER

Submarine

                 Let us begin first what a submarine is? A submarine is a special kind of boat that is able to go underwater. While most other boats are made to float, a submarine is made to do both: Travel on top of the water or beneath it. Now that’s interesting!  Submarines are incredible pieces of technology. Not so long ago, naval forces worked entirely above the water. But with arrival of submarines we can use the underwater sea as well. Jules Verne in his science fiction, 20,000 Leagues under the Sea, mentions a ship, Nautilus, which could dive beneath the waves and surface again when it wanted to. Even before submarines were thought about, Verne had created the blueprint of this technological marvel. Not only did he describe the machine, but he also explained, in great detail, how it worked. In fact, today's submarines use exactly the same technology as Verne's Nautilus did!

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Inertia

Why does a person sitting in a stationary vehicle get pulled back when the vehicle starts moving?

In order to understand this phenomenon you perform an experiment. Cover the mouth of a glass tumbler with a piece of cardboard and place a coin on it. Now push the cardboard with your finger so that the cardboard is thrown off the tumbler. Do you know what would happen? Along with the cardboard the coin would also fall off the glass. You should not worry and once again place the cardboard atop the glass along with a coin. Now flick the cardboard forcefully with your forefinger propelled with the help of your thumb and observe the consequences.

This time it would be quite different from what happened earlier. As soon as you strike the cardboard it would be thrown off but the coin would drop in the glass tumbler. What actually happens is this; the cardboard is thrown off with such a force that the coin fails to accompany the cardboard and the cause of the failure of the coin to move together with the cardboard is law of inertia. When a thing is stationary it remains in that stage till an external force makes it move. This is called Law of inertia.

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Fossils

Human beings have always tried to know their past. We have always been interested in finding out what the earth was like before we came into existence. But the past does not give up its secrets easily. It is buried in the earth for all time in the form of fossils. From the in depth study of fossils, we can gain important knowledge and evidence of life that existed in ancient times. From the study of fossils, scientists have been able to even find out the atmospheric conditions that existed in the distant past!!

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Aurora Lights

The term “Aurora” basically refers to a natural light at very high altitudes in the sky. The aurora borealis (the Northern Lights) and the aurora australis (the Southern Lights) have always fascinated mankind, and people even travel thousands of miles just to see the brilliant light shows in the earth's atmosphere. The auroras, both surrounding the north magnetic pole (aurora borealis) and south magnetic pole (aurora australis) occur when highly charged electrons from the solar wind interact with elements in the earth's atmosphere.

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Kuiper Belt

Since, the discovery of Pluto the Trans-Neptunianregion, also called as Edgeworth-Kuiper belt,  of our solar system was attracting scientists all around the world. Edgeworth-Kuiper belt, is similar to the asteroid belt although far more larger than the asteroid belt, it mainly contains the remnants of the solar system. The classical belt is residence of three dwarf planets –PLUTO, HAUMEA and MAKEMAKE.

Kuiper belt extends from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. “Triton” Neptune’s moon is also known to be originated from the Kuiper belt region; lots of studies over the topic have shown that the belt is dynamically stable. Pluto is the largest known member of the Kuiper belt, if the scattered disc is excluded .Often Kuiper belt is confused with the Oort-Cloud but reality is that Oort cloud is thousand times more distant than the belt is.Fredrick.c.leonard was the first person to suggest regarding the region .But, it was in 1951 Gerard Kuiper achieved a major breakthrough in the research.Later as the evolution takes place a hypothesis were proposed.

 The famous "dirty snowball" hypothesis for cometary structure thought that a "comet belt" might be massive enough to cause the purported discrepancies in the orbit of Uranus that had sparked the search for Planet X or at the very least, to affect the orbits of known comets. Observation, however, ruled out this hypothesis.

In 1977, Charles Kowal discovered 2060 Chiron, an icy planetoid with an orbit between Saturn and Uranus. He used a blink comparator; the same device that had allowed Clyde Tombaugh to discover Pluto nearly 50 years before. In 1992, another object, 5145 Pholus, was discovered in a similar orbit. Today, an entire population of comet-like bodies, the centaurs, is known to exist in the region between Jupiter and Neptune. The centaurs' orbits are unstable and have dynamical lifetimes of a few million years. From the time of Chiron's discovery, astronomers speculated that they therefore must be frequently replenished by some outer reservoir.

Further evidence for the belt's existence later emerged from the study of comets.It was in 1987 that puzzled by the emptiness of outer space scientists around the world started finding and vigorous research regarding the region particularly in US. Through studies a final hypothesis was proposed that the scattered disc was created when Neptune migrated outward into the proto-Kuiper belt, which at the time was much closer to the Sun, and left in its wake a population of dynamically stable objects which could never be affected by its orbit (the Kuiper belt proper), and a population whose perihelia are close enough that Neptune can still disturb them as it travels around the Sun (the scattered disc). Because the scattered disc is dynamically active and the Kuiper belt relatively dynamically stable, the scattered disc is now seen as the most likely point of origin for periodic comets.

The size structure and mas of Kuiper Belt was further found out and it was recorded that at its fullest extent, including its outlying regions, the Kuiper belt stretches from roughly 30 to 55 AU. However, the main body of the belt is generally accepted to extend from the 2:3 resonance at 39.5 AU to the 1:2 resonance at roughly 48 AU. The Kuiper belt is quite thick, with the main concentration extending as much as ten degrees outside the ecliptic plane and a more diffuse distribution of objects extending several times farther. Overall it more resembles a torus or doughnut than a belt. Its mean position is inclined to the ecliptic by 1.86 degrees.

The presence of Neptune has a profound effect on the Kuiper belt's structure due to orbital resonances. Over a timescale comparable to the age of the Solar System, Neptune's gravity destabilizes the orbits of any objects which happen to lie in certain regions, and either sends them into the inner Solar System or out into the scattered disc or interstellar space. This causes the Kuiper belt to possess pronounced gaps in its current layout, similar to the Kirkwood gaps in the asteroid belt.

The number and variety of prior speculations on the nature of the Kuiper belt have led to continued uncertainty as to who deserves credit for first proposing it. But, still it continues to be discovered through and remains a topic of debate.

-RUTURAJ BARGAL

Tsunami

Introduction:

Tsunami is a Japanese word with the English translation, "harbor wave." Represented by two characters, the first character, "tsu," means harbor, while the second character, "nami," means "wave." It is a powerful series of waves caused by a disturbance under water. Waves travel through ocean and cause devastation when they reach land.

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Reflection of Sound

           Just like light, sound also travels in form of waves. But unlike light sound requires a definite medium. Sound waves are mechanical waves.  Similar to light, sound waves also get reflected when they hit an obstacle. The geometrical laws for reflection of sound waves are the same as those for light waves. Multiple reflection of sound is the process in which sound waves bounces off obstacles and reflects many times before reaching the destination. Human ear can hear sound waves till the range of 20Hz to 20000Hz.Sounds of frequencies below 20 Hz are called infrasonic sound or Infrasound. Sounds of frequency above 20000 are called ultrasonic sound or ultra sound.

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The Archimedes' Principle

Archimedes of Syracuse (Greek: Ἀρχιμήδης; c. 287 BC – c. 212 BC) was a Greek mathematician, physicist, engineer, inventor, and astronomer. Although few details of his life are known, he is regarded as one of the leading scientists in classical antiquity.

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Refracting Telescope

We all very well know that a telescope is used to see distant astronomical objects and bodies. But have you ever wondered what it is made of which enables us to see the distant objects so clearly? Its working is based just on the simple principles of optics as is discussed below.

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Rain

We all know what Rain is. It is one of the most exciting season of the year. But have you ever wondered where does rain come from? Where all the pouring water comes from?

We will do a small experiment to understand the concept of Rain. Take an aluminium kettle and cover it with a lid in such a way that there remains a little gap between the lid and the vessel for the exit of the steam. Now boil the water till steam starts coming out. Take some pieces of ice or chilled water in a pan with a handle.

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Halley's Comet

A comet is a bright object with a long tail that travels around the sun. Comets are two types- short period comets and long period comets. Short period comets are those whose period of revolution around sun is less than 200 years. Among short period comets Halley’s Comet is the most famous one. This comet is visible from earth for every 75 to 76 years. This is clearly visible to naked eye maximum twice in a human lifetime. Other comets are brighter and spectacular but only appear for thousands of years.

There were recordings of Halley’s Comet even from 240 BC. People of that period predicted that it was a messenger sent by god. Some scholars who made research in early ages concluded that it was an object which is far beyond moon and believed that it travels in a straight line through solar system.

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How does a fan produce air?

The very first thing that is to be known is that a fan does not actually produce any air on its own but it just pushes the air behind it towards you.

Ok, suppose you were to DESIGN a fan. You need to devise a mechanism to push air towards you. Everyone would have seen hand-fans at work (especially during IRRITATING power cuts). In hand fans, we just keep flapping it or waving it .

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Extinction of Dinosaurs

             Dinosaurs are wonder to both adults and children. It is hard to imagine that such a large creature roamed on earth once upon a time. They were most successful creatures than any other group of animals and mammals. They ruled our planet for about 150 million years. They are probably giant killing machines. But 65 million years ago they suddenly disappeared from the earth. What had actually happened at that time? Did the dinosaurs face terrible catastrophic conditions on earth? It is one of the great mysteries of paleontology.

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Eclipses

Eclipse is a astronomical phenomenon that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer.

Eclipse is a derived from a greek word and means "to abandon", "to darken"

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Evolution of Bicycles

Walk up to your bicycle and ask yourself the question, is there any other design possible for my bike?

·                     Can I make it faster, cooler and smarter?

·                     Why is the design the way it is?

·                      Why do I need 2 wheels?

·                     Do they have to be of the same size?

·                      Why is the seat somewhere in the middle of the wheels?

·                      Why is the handle bar on the front wheel?

·                      Why can’t we control the back wheel in the same way?

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Andromeda Galaxy

The Universe is made up of many Galaxies, Stars and other things. Do you have any idea that which is the nearest galaxy our own milky way? It is the Andromeda Galaxy.

It is around 2.5 million light years away from earth.  Yes it’s the big spiral known as ANDROMEDA GALAXY also known as MESSIER it is the galaxy nearest to our MIKYWAY. Andromeda is the largest galaxy of the Local Group, which consists of the Andromeda Galaxy, the Milky Way, the Triangulum Galaxy, and about 30 other smaller galaxies. Although the largest, Andromeda may not be the most massive, as recent findings suggest that the Milky Way contains more dark matter and may be the most massive in the grouping.

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Capacitor Problems

What would happen if you keep a block of wood between the two plates of a capacitor? How would the capacitance associated with the system adjust to this ‘intrusion’? Read on to find out how the capacitance involving combinations of such ‘dielectrics’ is evaluated.

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The Doppler Effect

Two countries A and B are at war with each other. Since both of them are equally matched in air and on land, they decide to fight at sea. You are a citizen defending country A which has better naval fleet than B. On the verge of defeat, as a last resort, country B sends one of their best submarines to attack from below. How do you employ the physics of sound as a weapon at this decisive moment, to save your nation? Read on to discover...

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Non-Conserative Induced Electric Field

We always encounter situations that deviate from the normal. Doesn’t it seem bizarre that a voltmeter connected across two points can actually show two different values depending on how it is connected? Sounds strikingly similar to the mechanical equivalent, where friction does varying amounts of work between two points depending on the path taken to move a body. Doesn’t it? Yes. The culprit is a non-conservative force in action.

Consider a circuit with a 10V battery and two resistors R₁=80 ohms and R₂ =20 ohms. If we are to calculate the current i through the circuit, applying the Kirchhoff’s loop law yields this:

If we were to find the potential difference between A and B as shown,we have two paths at our disposal, namely, 1 & 2:

By following path 1, we get V_a - V_b = 80(0.1) = 8 V

By following path 2,we get V_a - V_b = 10 - 20(0.1) = 8 V

Any path taken gives the same value of V_a - V_b. With further deductions, we can understand that this must hold good because electric field produced by the battery or, in general, any static charge is conservative.

Now, consider the case of magnetically induced electric fields. Are they conservative or non-conservative? To analyze their nature, utilize a similar setup without the battery. Instead, there is a changing magnetic field through the loop.

Consider the instant when the rate of change of the flux through the loop is exactly 10V. According to Faraday’s Law, EMF induced in the loop will be 10V. Again, we find the current i through the loop, which comes out to be 0.1 A. Let the two digital voltmeters be connected across the two resistors as shown.

We may judge that both the voltmeters will show the same reading as they are connected across the same points. Surprisingly, this is not so!

The voltmeters show entirely different readings .This is rationalized by these calculations.

We found that the current in the circuit is 0.1A. So, if we go trace path 1 we get

V_a - V_b = 80(0.1) = 8 V,

which will be the same reading as that of the voltmeter V1.

By path 2,we get

V_a - V_b = -20(0.1) = -2 V

Evidently, this dissimilarity points to the fact that we ‘removed’ the battery voltage source (and replaced it with something else). So, voltmeter V₂ shows -2V.

Summing it up, we get two voltmeters attached across the same two points showing different readings. What is the mystery behind this baffling complication?

Well, magnetically induced electric fields are non-conservative. When we calculate potential difference between two points taking two different paths, we get different answers unlike the electric field created by charges. Thus, magnetically induced fields are non-conservative in nature and forms loops. This property is different from the conventional electric fields, which emerge at a positive charge and end at a negative charge. Can you find out some more anomalies of non-conservative fields?

Our Solar System

Mankind has always been making discoveries about the celestial bodies that surround us. The solar family is a blend of opposites – of unimaginable giants, of hundred metre asteroids, of extremely hot lands and of freezing cold atmospheres. So, who are these members journeying around the sun?

OUR SOLAR SYSTEM

The solar system consists of the sun and other astronomical bodies orbiting around it under the influence of its gravitational field. These celestial bodies include the planets, their satellites and meteorites. While satellites revolve around their planets, and the planet around the sun, it is intriguing to note that the solar system too, keeps revolving around the nucleus of Milky Way at a distance of about 30,000 light years. So, what is a light year? To analyse astronomical distances the units that we come across daily viz., metre, foot are extremely inadequate. Instead, imagine the distance light could travel in a year when it can cover 30,00,00,000 m in a second! As the name says, this is what is termed as a light year.

The sun, which has a diameter that can fit hundred and nine earth-sized bodies, is the ultimate fuel for life on earth. Contrary to the popular belief that the sun is a stationary star, it moves with the solar system at a spectacular speed of 828,000 km/hr!

What seem to be merely floating about the Sun, are not just some spherical masses of various sizes. Unique in their own way in almost every aspect, these distant bodies have kept people right from the ancient times to the modern ages wondering about their veiled mysteries, giving rise to fascinating mythologies and startling scientific discoveries.

MERCURY VENUS

Mercury, the planet closest to the sun is a god of trade in Roman mythology. (Doesn’t the name sound similar to ‘merchant’?) Venus, though resembles the Earth in many ways, is highly uninhabitable – it has a dense atmosphere of carbon-dioxide and sulphur brought about by extensive volcanic activity.

MARS JUPITER

The red planet Mars, is usually associated with wars and masculinity in mythologies. Mars has the same colour as that of rust. Can you now guess what could be the compound behind its brilliant hue?

While planets closer to the sun, namely, Mercury, Venus, Earth and Mars are ‘terrestrial’, the outer planets, Jupiter, Saturn, Neptune, and Uranus are actually ‘gas’ giant. (Pluto is no more considered a planet now.) In fact, the ringed-planet Saturn is so gaseous that, it is buoyant enough to float on water! (No, Jupiter sinks!) The answer lies in Archimedes’ Principle. The hint is, Saturn’s average density is 0.7g/cm³ and Jupiter’s is 1.4g/cm³.

SATURN

Accompanying these planets, we have a belt of asteroids located roughly between Mars and Jupiter. These bodies have no regular shape and can have mean diameters of more than 400km.

URANUS NEPTUNE

Uranus, the god of the skies in Greek mythology, has an almost horizontal axis of rotation! Neptune is a near-twin to Uranus. This was the first planet to be ‘mathematically predicted’ from unexpected changes in Uranus’s orbit.

- Article by Akshay Nemande

- Edited by Vaishnavh