Category Scientist & Invensions

The significance of the Newtonian reflector does not lie in the discovery of new celestial bodies or celestial phenomena. Newton neither discovered the moons around Jupiter like Galileo nor did he plot the return of a comet – like Halley. However, the Newtonian reflector and Newton’s theory of universal gravitation made an invaluable contribution: they tied together Mathematics, Astronomy, and our understanding of the universe.

He mathematically established that gravitation was a two-way operation. While the Earth pulled on a falling apple, the apple too pulled on Earth. This was seen, calculated and confirmed in the motions of heavenly bodies. It was made possible by the science of the reflector telescopes which can be credited to Newton. The work of Copernicus and Galileo were carried through by Newton and his telescope.

While it is commonly assumed that Newton invented the first reflector telescope, claims to the contrary are also there. The Italian monk Niccolo Zucchi claimed to have experimented with the idea as far back as 1616. It is possible that Newton read James Gregory’s 1663 book Optica Promota which contained designs for a reflecting telescope using mirrors. Gregory had been trying to build such a telescope, but he did not succeed. Ultimately, Newton’s telescope was the one that worked well and brought reflectors to the scientific world.

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The first successful practical reflecting telescope was built by Newton. Until then telescopes were large unwieldy instruments. The design of the telescope was recast by Newton on the basis of his theory of optics. He used mirrors instead of lenses and the result was a new telescope 10 times smaller than the traditional ones.

Earlier also many efforts were made to make more powerful telescopes using larger lenses. They were unsuccessful as the lens kept producing coloured rainbows around bright objects like the Moon and the planets. The coloured fringes formed due to the unequal refraction of colours by the lens were unavoidable in simple telescopes.

Newton was under the assumption that no lens could rectify this issue. Though this was a mistaken assumption, it led him to use a mirror to form an image and thereby to build a reflecting telescope. This is now called the Newtonian reflector. A curved mirror brings rays of light to a focus and forms an image by reflection (whereas a lens does it by bending or refraction). Some of the largest telescopes used today are based on the telescope made by Newton in 1668.

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The laws of motion are applicable even in outer space. Newton’s Second Law states that force is needed to increase or decrease the speed of a body. This implies that astronauts must learn to push themselves through their spacecraft, or else they will float around helplessly. They also need to remember to stop themselves as they near their destination or else they’ll keep moving till they hit something.

During their first attempt, astronauts usually end up a little worse for the wear after stumbling around the spacecraft. Unlike humans, animals flown to space often fail to learn this. A set of new-born quails aboard Russia’s Mir space station couldn’t adapt to life in space and died in a few days. Newton’s Third Law too has application for astronauts. The law states that for every action, there is an equal and opposite reaction. While turning a screw, astronauts have to anchor themselves to a wall, or else they’ll be the ones twisting. Even the mildest action like typing at a computer keyboard will send an astronaut floating away. To remedy this problem, workstation on the international space station has restraining loops for the crew to anchor their feet.

Though it may seem like the laws of motion are different in space and on Earth that is not the case. The overwhelming force of Earth’s gravitational field simply masks its exact effects. Gravity plays an astonishing part in many phenomena we take for granted. For instance, hot air (which is lighter than cool air) rises, and a convection current is formed which enables natural air circulation in our houses. In space however, nothing is lighter than anything else and ordinary convection currents do not exist. Thus, to make sure that the astronauts don’t suffocate due to carbon dioxide accumulation, a ventilation fan is installed to facilitate air circulation.

The International Space Station is a perfect example of the laws of motion. Though intuition and common-sense points otherwise, Newton realized that a bullet shot from a gun should continue to move indefinitely. On Earth, atmospheric friction slows the projectile while gravitational force pulls it to the ground. But the faster the bullet is shot, the farther it will travel before falling. And if you can manage to shoot something at a speed of around 11.2 km/s, it will never finish its trajectory. It will instead orbit the Earth in a state of perpetual free fall. This particular velocity (11.2 km/s) cancels the pull of Earth’s gravity and is used to launch spacecraft.

Even fire is not exempt from the laws of motion in space. Behaviour of weightless flames is rather different from those on Earth. However, such a fire is best limited to the lab as fire aboard a spacecraft can have catastrophic effects.

The sizes of rockets range from small fireworks used by ordinary people to massive Saturn Vs that once carried payloads toward the Moon. Newton’s third law of motion explains the propulsion of all rockets, jet engines, deflating balloons, and even the movement of squids and octopuses.

The engines of rockets need to overcome both the pull of gravity and the inertia of the rocket as stated in the first law. According to Newton’s Third Law, “every action has an equal and opposite reaction”. A rocket is pushed forward by the push of the burning fuel at its front. This also creates an equal and opposite push on the exhaust gas backwards.

Once they’re in motion, they won’t stop until a force is applied. As per Newton’s second law, as mass of the object increases, the force needed to move it also increases. The larger a rocket, the stronger the force (for instance, more fuel) to make it accelerate. A space shuttle requires around three kilograms of fuel for every kilogram of payload it carries.

Astronauts in space must also keep the laws of motion in mind. During his pioneering orbit of the Earth in 1961, Russian cosmonaut Yuri Gagarin was the first to experience the practical effects. Gagarin put down his pencil while writing his log. In keeping with Newton;s first law, by which the planets move around the Sun, the pencil floated out of reach. He ended up completing the log using a tape recorder. Now astronauts keep their equipment tethered to a surface with Velcro or bungee straps.

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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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