RAIN, UMBRELLA,AND VECTORS

First, we must know about relative velocity. Say, you are travelling in a express train at the speed of 100km/hour. In the next track another train is moving at the speed of 120km/hour. Now subtract your speed (100) from 120 km/hour. You get 20km/hour. That means, another train is running at the speed of just 20km/hour with respect to you. Hence it will apear to go slowly for you.

Say, rain is falling vertically at the speed of 4 kmph. Draw a 4 cm arrow pointing downwards. It is the vector representing rain's speed.
You are fast walking at the speed of 6 kmph towards east. Draw 6 cm arrow from the head of rain vector representing your speed. To find the relative velocity, we have to subtract. Hence reverse your vector (-6cm) towards west side. If we now add both the vectors, we will get the relative velocity.

To add, complete the triangle, the third side gives the result of addition.(triangular law of vector addition).The length of the third side is found to be 7.2 cm and it makes an angle 33.7 with the horizontal. It means, the rain is falling at the increased speed of 7.2 kmph slantingly at an angle 33.7 degrees in your view. When you run in the rain, it will splash in your face. If you hold the umbrella at the proper angle, you can save your face.
For the same reason, the rain falls slantingly across the train's glass window. Also the boat appears to go at an angle, when it crosses a flowing river.

This is the one use of vectors. When a quantity has a direction, we go for vectors. Geometry is the basis of vectors. But one can solve problems just using formulas.

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THE EARTH, A SUPER ORGANISM

JOIN MY COURSE: "Become a programmer in a day with python" A man called 'love lock' (what a name) proposed a theory called Gaia theory, named after Greek Goddess. It says, "Earth is a self-regulating organism like a human being. The organic life in it interacts with in-organic matter and maintains atmosphere, temperature and environment". Hence the earth is still suitable for the life to thrive. Imagine, in a particular place, there are lot of flowers. Some flowers are white and some are darkly coloured. We know, white reflects light and heat while dark absorbs the same. White flowers can thrive in hot climate. But dark flowers requires cold climate. The absorption and reflection balances and the environment reaches average, warm temperature at which both the flowers can co-exist. This is the essence of "Gaia" theory. On our earth, the oxygen constitute 20% of the atmosphere. The oxygen level is always mai

THE PARABOLA

A jet of water shooting from a hose pipe will follow a parabolic path. What is the so special about parabola. Y= x^2 Draw a graph for the above equation. It will result in a parabola. This parabola is also called unit parabola. Any equation involving square will yield a parabola. Example: Y = 2x^2 +3x+3 (also called quadratic equation) X= 2 and -2, both satisfies the equation 4 = X^2. Parabolic equations always have two solutions. Any motion taking place freely under gravity follows parabolic path. Examples: An object dropped from a moving train, A bomb dropped from flying plane, A ball kicked upwards. If a beam of light rays fall on the parabolic shaped mirror, they will be reflected and brought to focus on a point. This fact is made use of in Dish Antenna, Telescope mirrors, etc. Inverted parabola shape is used in the construction of buildings and bridges. Because the shape is able to bear more weight. A plane

DISORDER IS THE "ORDER OF THE DAY"

Imagine a balloon full of air. The air molecules are moving randomly inside the balloon. Let us pierce the balloon with a pin. The air rushes out. Why should not the air molecules stay inside the balloon safely and ignore the little hole? That is not the way the world works. The molecules always "want to occupy as many states as possible". Hence the air goes out in the open to occupy more volume. The things always goes into disorder (entropy) and the disorder increases with time. The above statement is what we call "second law of thermodynamics". Consider a cup of coffee on the table. Suppose the heat from entire room flows to your cup of coffee, the coffee will boil and the rest of the room will freeze. Freezing means bringing things to order and arrangement. It violates the second law. Hence it will never happen. Hence heat must flow from high temperature to low temperature and not the other way. The air molecules in y

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