Tutor profile: Akash P.
Subject: Physics (Newtonian Mechanics)
The wide misconception of Newton's third law.
We generally state Newton's third law as "To every action, there is an equal and opposite reaction". There is nothing wrong with this statement. The problems come while giving examples for the statement. Let us consider a case of an apple falling on Newton's head (which actually never did). We say that Apple was attracted to the Earth by Newton's law of Gravitation and that is true. Consider the apple fell on Newton's head had a mass of 100 g (Gram), so the corresponding gravitational force applied on the apple is 1 N (Newton), from Newton's second law (F = ma) apple accelerate towards earth at nearly 10 m/s^-2(meter per second squared). What we really miss is the effect of apple on Earth. By Newton's third law apple also exerts equal and opposite force on the Earth. The Earth has of approximately 6x10^24 kg and again by Newton's second law Earth accelerate towards apple at 1.7x10^-25 m/s^-2, which is highly negligible but what we really neglect is the deeper sense of the concept. Such concepts are so deeply rooted in the nature that it works on every scale, from small atoms to the heavenly bodies. Nature never misses out.
Did you ever wonder how do we know about the interior of stars even though we can't see whats inside?
At first, we can not see inside stars. Second, even with the most powerful telescope we only see stars as point objects only. So how do we know whats going inside stars??? When we observe stars through any telescope we look for the number of photons gathered by from stars in a particular amount of time, i.e, how much light is emitted by a star in a unit time (flux). From brighter object, we receive more light whereas from dimmer objects we receive less light. Later we look for the fact that in which part of the electromagnetic spectrum does it give out more light. In other words, we look at its blackbody spectrum after processing some data. For this, we have to gather data from different telescopes for the same object but in different regions of the electromagnetic spectrum. That was some very rough idea about what information we seek while studying a star. Coming to the question. We begin with some theoretical models which describe the interior of a type of star and how any changes within the star effects its outer layer (the one which we observe). In time if we observe the predicted effect then we conclude that particular theoretical model is correct so far with some deviation from reality (which is always there). One way to confirm a theoretical model is by observing the pulsation of the star. Most of the all-stars pulsate with some complex frequencies. This pulsation generates some waves called g-mode waves (gravity waves) and p-mode waves (pressure waves). Due to this the amount light radiated by star changes accordingly. This changes in brightness have a wide variety of periodicity. Some stars show pulsations with a period of minutes while some pulsate with period of months, depending upon the interior of stars and some other factors. If a theoretical model is correct then pulsation, i.e., changes in brightness will be observed accordingly. This is similar to understanding the interior of the Earth using waves generated by earthquakes.
What are zodiac signs and why is it important? let's learn it through visualization.
Let's say you have 13 friends, whose names are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricorn, Aquarius, Pisces and Sun (not necessary to remember all names right now). You asked them to stand in a circle except for Sun. Now make the sun to stand at its center and you stand anywhere else within that circle but you have to face towards Sun. Let's say your name is Earth. As we know the real Earth moves around the Sun. So, you also start moving around the Sun that you have(but remember, you have to keep your face towards Sun). While moving in a circle notice that there is always some portion of someone hiding behind the Sun, whether it is Aries, or Capricorn or Scorpius or any other. There is one more thing you have to remind yourself is we don't see Stars during the daytime because of the brightness of Sun. So, in reality, every time the Earth moves around the Sun there is always some group of stars hiding behind the Sun. There are only 12 groups of stars which periodically hide behind the Sun. Those groups of stars are called Zodiac signs and they are your friends which we named in the beginning. There more details involved like the size of the zodiac signs and all which you can explore on your own.
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