My Science School

The publication of Newton’s laws of motion proved to be greatly advantageous for scientists and engineers across the globe. His laws have found applications in everything with moving parts whether it is the design for machines and scientific equipment or clocks and wheeled devices. On the basis of these laws, it was possible to predict whether a machine would work even before it was built.

In the nineteenth century, British engineer lsambard Kingdom Brunel, built huge steamships and suspension bridges using Newton’s laws. James Watt couldn’t have made the first working steam engine without the laws of motion. We use these laws even today to solve the problems related to the construction of modern structures and tall buildings.

Newton’s laws of motion are still the basis of modern mechanical engineering. Its application is spread across different fields. Everyone from oil-well technicians to space engineers and car designers to satellite constructors utilise these laws.

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Newton presented the three laws on motion in 1687 in his book Philosophiae Naturalis Principia Mathematica. The universal laws of motion describe the relationship between any object, the forces acting upon it and the resulting motion.

The first law of motion or the law of inertia states that if a body is at rest or moving at a constant speed, it will continue in that state unless it is acted upon by an external force. This tendency of massive bodies to resist changes in their state of motion is called inertia.

Using this law of motion, we can explain why a car stops when it hits a wall but the human body in the car will keep moving at the earlier speed of the car until the body hits an external force, like a dashboard or airbag.

Similarly, an object thrown in space will continue infinitely in the same speed, on that path until it comes into contact with another object that exerts force to slow it down or change direction.

Newton’s second law of motion is F=ma or force equals mass times acceleration. For example, when you ride a bicycle, your pedalling creates the force necessary to accelerate. This law also explains why larger or heavier objects require more force to move and why hitting a small object with a cricket bat creates more damage than hitting a large object with the same bat.

The third law of motion is, for every action, there is an equal and opposite reaction. This is a simple symmetry to understand the world around us. When you sit in a chair, you are exerting force down upon the chair, but the chair is exerting an equal force to keep you upright.

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The universal law of gravitation was proposed by Newton in 1687. He used it to explain the observed motions of the planets and the Moon. Mass is a crucial quantity in Newton’s law of gravity.

According to the law, every particle in the universe attracts every other particle with a force. This force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. It implies that the attractive force of gravity increases with the increase in mass and decreases with the increase in distance.

For example, if we transported an object of the mass ‘m’ to the surface of Neptune, the gravitational acceleration would change because both the radius and mass of Neptune differ from those of Earth. Thus, our object has mass ‘m’ both on the surface of Earth and on Neptune, but it will weigh much more on the surface of Neptune because the gravitational acceleration there is 11.15 m/s2. Thus, Newton was able to mathematically prove Kepler’s observations that the planets move in elliptical orbits.

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Isaac Newton was the first to connect gravity to planets other than Earth. He proposed that other planets and stars also have gravitational force. In fact, it was present everywhere in the universe. Planets including Earth remain in their orbits and rotate around the Sun due to the force of gravity exerted by the Sun. It is Earth’s gravitational force that keeps the Moon moving in its orbit. The pull of the Earth causes Moon to travel in a curved path. 

The same principle applies to satellites in orbit around Earth. If Earth had no gravity, the satellites would fly off into space. We can very well say that gravity is what binds the solar system together.

The planets also disturb each other’s orbits due to gravity. These disturbances are termed as ‘perturbations.’ Scientists discovered Neptune because of the unexpected perturbations observed in the orbit of Uranus.

The story commonly told is that Newton saw an apple falling from a tree and discovered gravity while thinking about the forces of nature. Another version says that the apple landed directly on his head. Either way, Newton realized that there must be some force acting upon all objects, causing them to fall.

He also considered the moon which should actually fly away from Earth in a straight-line tangent to its orbit if there hadn’t been a force binding it to Earth. He concluded that the moon is a projectile rotating around the Earth due to gravitational force.

Newton called this force ‘gravity’, something that pulls everything to the ground. The weight of an object is the measurement of the strength with which it is being pulled by gravity. Or in other words, gravity gives weight to physical objects. The reason we can keep our feet firmly on the ground and walk around is gravity. It is what stops objects from flying off into space.

Gravity is the force that had the effect of pushing on the planets and was equal to the pull of the sun. It is in fact responsible for many of the large-scale structures in the universe. Newton also explained the astronomical observations of Kepler using the concept of gravity.

Newton was famously slow in publishing his researches. His New Theory of Light and Colours appeared in the Philosophical Transactions of the Royal Society only in 1672. The publication resulted in a dispute with Robert Hooke who was a dominant figure in the Society.

Newton’s experiments with white light had many practical applications that benefited the common man. Spectacles were a luxury only affordable for the upper classes in the seventeenth century. Even then, the glasses were of poor quality. In the decades following the publication of Newton’s research, amazing advancements were made in the design and manufacture of lens and spectacles.

Similarly, Newton’s findings were also applied to create sophisticated microscopes. Though microscopes existed even during his time, they were basic models that produced blurred images. With the development of better microscopes came breakthroughs in medicine and biology.

However, the most resounding impact of Newton’s work was perhaps the creation of an entirely new science, the science of spectroscopy. Spectroscopy is the study of light in relation to the length of the wave that has been emitted, reflected or shone through a solid, liquid, or gas.

Newton’s discoveries revolutionized our understanding of the most common aspects of nature such as light. Prisms were seen as trivial toys used for fun in laboratories until Newton came across them. He conducted a series of experiments with sunlight and prisms after getting a prism at a fair in 1664.

Newton made the astonishing discovery that clear white light was composed of seven visible colours. The visible spectrum, the seven colours of the rainbow, was scientifically established by Newton. This discovery opened new vistas in optics, physics, chemistry, and the study of the colours in nature.

One bright sunny day, Newton darkened his room and made a hole in his window shutter, allowing just one beam of sunlight to enter the room. He then took a glass prism and placed it in the sunbeam. The result was a spectacular multi-coloured band of light just like a rainbow.

Newton believed that all the colours he saw were in the sunlight shining into his room. He thought he then should be able to combine the colours of the spectrum and make the light white again. To test this, he placed another prism upside-down in front of the first prism. He was right. The band of colours combined again into white sunlight. Newton was the first to prove that white light is made up of all the colours that we can see.

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We may remember Newton mostly in association with the theory of gravity and the story of the apple tree. But he was also a great mathematician on par with legendary figures like Archimedes and Gauss. Newton’s contributions paved the path for numerous mathematical developments in the succeeding years.

Until Newton, algebraic problems where the answer was not a whole number posed a problem for mathematicians. The formula published by Newton in 1676 called ‘binomial theorem’ effectively resolved this issue. It has been said that through Newton’s works, there was remarkable advancement in every branch of mathematics at the time.

Newton (along with mathematician Gottfried Wilhelm von Leibniz) is credited with developing the essential theories of calculus. He developed the theory of calculus upon the earlier works by British mathematicians John Wallis and Isaac Barrow, and prominent mathematicians Rene Descartes, Pierre de Fermat, Bonaventura Cavalieri, Johann van Waveren Hudde and Gilles Personne de Roberval.

While Greek geometry was static, calculus allowed mathematicians and engineers to make sense of the dynamic world around them. They could now make sense of motion such as the orbits of planets and the flow of fluids.

Many modern historians believe calculus was developed independently by Newton and Leibniz, using different mathematical notations. Leibniz was however, the first to publish his results.

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With the outbreak of the bubonic plague, Cambridge University closed its doors in 1665. As a result, Newton was forced to return home to Woolsthorpe Manor where he ended up staying with his mother for over a year. In the peaceful countryside, he concentrated on the scientific problems about which he had wondered during his post graduate years.

Some of his greatest discoveries such as the laws of gravity, laws of motion, and the components of white light had their origin during this time.

It is said that Newton was sitting in the orchard when he saw an apple falling from a tree. Contrary to popular versions of this event, there is no evidence to suggest that the apple had fallen on his head. Pondering upon what he saw, Newton wondered why apples fall straight to the ground rather than going upwards or sideways. Following this line of thought, he finally formulated the law of universal gravitation.

This was the account of his discovery given by Newton himself to his acquaintances including the French philosopher Voltaire; his assistant at the Royal Mint, John Conduitt who was the husband of his niece Catherine Barton; his friend William Stewkeley; and Christopher Dawson who was a student at Cambridge. The note on Newton’s life collected by John Conduitt in 1726 contains the first written account.

The year he spent in Woolsthorpe later came to be called his annus mirabilis (year of wonders). Newton returned to Cambridge in 1667.

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Isaac Newton and Albert Einstein are two of the most prominent figures in the development of modern science. Newton’s contributions to science establish him as one of the greatest scientists of all time. Many of the theories and scientific principles we study today were developed by Newton.

He proposed the theory of gravity and calculus, discovered the components of white light and made breakthroughs in optics with the reflecting telescope. His Laws of Motion are the basis for physics.

Newton’s binomial theorem tells us how expressions in the form (a+b)n should be expanded. His work Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) (1687) is considered to be a seminal piece of literature in the history of modern science. He has also written another book, titled Opticks, about light.

Newton’s discoveries have applications in everyday technology from toys and television to lasers and life-changing medical devices. Everything from high-rise buildings to Formula One racing cars utilizes the ideas proposed by Isaac Newton.

Calculus and binomial theorems proposed by Newton are used by space engineers to send a rocket to the moon, more than 3,84,400 km away, and ensure its safe return. In the same way, economists predict the fluctuation of currencies using these very same branches of mathematics!

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Newton was born on 4 January 1643 in the village of Woolsthorpe, Lincolnshire in England. He belonged to a prosperous family engaged in farming for generations.

There was no tradition of giving formal education in his family. Though Newton’s relatives on his mother’s side were educated, both his father and grandfather were illiterate. His father, also named Isaac Newton, passed away three months before his son was born.

Since he was born premature, the doctor who attended his birth was not sure the child would survive. Though they were an affluent family who lived in the comforts of a country house, Newton’s mother must have found it difficult to raise a sickly child by herself.

Within two years, his mother Hannah Ayscough remarried a well-to-do minister named Barnabas Smith and moved to another village. Young Isaac was left behind to the care of his grandmother. The mother and son reunited after the death of Smith when Newton was 12 years old. Newton had three step-siblings (Mary, Benjamin and Hannah) from his mother’s second marriage.

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In 1774, the English chemist Joseph Priestley announced that he had discovered ar element within the air. Previously it had been thought that air itself was an element. However, Priestley’s achievement is an example of something that happens quite frequently in science. Although Priestley undoubtedly did discover the presence of oxygen, he was not the first to do so. A Swedish chemist called Carl Scheele had discovered it some months before, and it was not until some months later that a French chemist, Antoine Lavoisier, used Priestley's work to explain what oxygen is and its importance in respiration and combustion. He also gave oxygen its name. The sharing of scientific knowledge moves our understanding of the world forward. No one person can put together all the pieces of the jigsaw puzzle.

Priestley entered the service of the Earl of Shelburne in 1773 and it was while he was in this service that he discovered oxygen. In a classic series of experiments he used his 12inch "burning lens" to heat up mercuric oxide and observed that a most remarkable gas was emitted. In his paper published in the Philosophical Transactions of the Royal Society in 1775 he refers to the gas as follows: "this air is of exalted nature…A candle burned in this air with an amazing strength of flame; and a bit of red hot wood crackled and burned with a prodigious rapidity, exhibiting an appearance something like that of iron glowing with a white heat, and throwing sparks in all directions. But to complete the proof of the superior quality of this air, I introduced a mouse into it; and in a quantity in which, had it been common air, it would have died in about a quarter of an hour; it lived at two different times, a whole hour, and was taken out quite vigorous."

Although oxygen was his most important discovery, Priestley also described the isolation and identification of other gases such as ammonia, sulphur dioxide, nitrous oxide and nitrogen dioxide.

The Leeds Library holds important archival material on Priestley's time there. It was while he was in Leeds that he began his most important scientific researches namely those connected with the nature and properties of gases. A bizarre consequence of this is that Priestley can claim to be the father of the soft drinks industry. He found a technique for dissolving carbon dioxide in water to produce a pleasant "fizzy" taste. Over a hundred years later Mr Bowler of Bath benefited from this when he formed his soft drinks industry.

Priestley should be included in any pantheon of scientists. The bicentenary of his death is an opportune time to reassess his life and work and several events are planned during the year. He possessed enormous scientific skills and originality of thought as well as having the courage to promote unpopular views. He was a man of rare insight and talent.

Sir Edmond Halley’s name is remembered because he was the first person to predict that the comet he saw in 1682 followed a path that would bring it within sight of the Earth again in 1758. Unfortunately, he was no longer alive at that date to see his prediction come true, but his achievement was recognized and his name attached to the comet ever afterwards. In fact, the comet can be seen from Earth every 75-79 years. Its appearance was first recorded by Chinese astronomers in 240BC. The comet, still an unexpected visitor, also appeared in 1066 and was embroidered onto the Bayeux Tapestry, which records the Norman invasion of England.

Edmond (or Edmund) Halley was an English scientist best known for predicting the orbit of the comet that was later named after him. Though he is remembered foremost as an astronomer, he also made significant discoveries in the fields of geophysics, mathematics, meteorology and physics.           

In 1704, Halley was appointed the Savilian professor of geometry at Oxford. Continuing his work in observational astronomy, Halley published "A Synopsis of the Astronomy of Comets" in 1705. In this work, he showed that comet sightings of 1456, 1531, 1607 and 1682 were so similar that they must have been the same comet returning. He predicted that it would return in 1758.

In 1716, Halley devised a method for observing transits of Venus across the disk of the sun in order to determine the distance of Earth from the sun. He also proposed two types of diving bells for exploring underwater. In 1718, by comparing star positions with data recorded by the Greek philosopher Ptolemy, he deduced the motion of stars.

In 1720, Halley succeeded Flamsteed as Astronomer Royal. He continued to make observations, such as timing the transits of the moon across the meridian, which he hoped would eventually be useful in determining longitude at sea.

Halley died Jan. 14, 1742, in Greenwich, England. He did not survive to see the return of what later was named Halley's Comet, on Christmas Day in 1758.

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At one time tens or even hundreds of years might have passed between a scientist’s discovery of a potentially useful fact or method and its use by a wide range of other people. Nowadays, the process is much quicker. This is partly because research is often very expensive and there is pressure to find a commercial use for an invention to help to pay for new research. Modem methods of mass production and global advertising also mean that new products can become popular very quickly.

Hundreds of years ago, news about new products travelled very slowly. Today, advertising is aimed at individual markets and ensures that as many people as possible are aware of what is available.

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Galileo Galilei (1564-1642) was an Italian scientist who worked on many mechanical problems but is perhaps best known for his astronomical observations. These supported the ideas developed by Nicholas Copernicus (1473-1543), a Polish scientist. He claimed that rather than the Sun orbiting the Earth, the Earth orbits the Sun. This idea went against the teachings of the Church, so Copernicus did not tell many people about it. Indeed, when Galileo spoke out in its support, he was put on trial and forced to withdraw his claim. Even today, scientific discoveries are not always popular when they go against long-held beliefs.

Italian astronomer Galileo Galilei provided a number of scientific insights that laid the foundation for future scientists. His investigation of the laws of motion and improvements on the telescope helped further the understanding of the world and universe around him. Both led him to question the current belief of the time — that all things revolved around the Earth.

The Ancient Greek philosopher, Aristotle, taught that heavier objects fall faster than lighter ones, a belief still held in Galileo's lifetime. But Galileo wasn't convinced. Experimenting with balls of different sizes and weights, he rolled them down ramps with various inclinations. His experiments revealed that all of the balls boasted the same acceleration independent of their mass. He also demonstrated that objects thrown in the air travel along a parabola.

At the same time, Galileo worked with pendulums. In his life, accurate timekeeping was virtually nonexistent. Galileo observed, however, that the steady motion of a pendulum could improve this. In 1602, he determined that the time it takes a pendulum to swing back and forth does not depend on the arc of the swing. Near the end of his lifetime, Galileo designed the first pendulum clock.

Galileo is often incorrectly credited with the creation of a telescope. (Hans Lippershey applied for the first patent in 1608, but others may have beaten him to the actual invention.) Instead, he significantly improved upon them. In 1609, he first learned of the existence of the spyglass, which excited him. He began to experiment with telescope-making, going so far as to grind and polish his own lenses. His telescope allowed him to see with a magnification of eight or nine times. In comparison, spyglasses of the day only provided a magnification of three.

It wasn't long before Galileo turned his telescope to the heavens. He was the first to see craters on the moon, he discovered sunspots, and he tracked the phases of Venus. The rings of Saturn puzzled him, appearing as lobes and vanishing when they were edge-on — but he saw them, which was more than can be said of his contemporaries.