WHAT IS ACTUALLY "HEAT"?

Automobile engines, ovens, chemical reactions work due to heat. How to see , feel and understand the heat?

We know all the substances are made up of molecules. When the molecules are in motion(moving, vibrating, rotating etc.,) the substance is said to carry heat energy.

Take a hot tea in a cup and put a cold spoon in it. We know the spoon will be heated up. What happens? The molecules are in fast random motion in the hot tea. These molecules collide with the molecules of the spoon and set them in vibration. Now we say heat is transfered from tea to spoon.

As a speed of the molecules increases(kinetic energy), the heat content of the substance increases and we say the temperature increases.

Even at freezing point (at 0 degree c), the molecules really do not freeze but move at low speeds. When all the molecules come to stand still, we say the temperature is absolute zero or 0 degree kelvin. At 0 degree k: no movement , no heat, no temperature.

We know radiation or waves also cause heat. The radiation behaves like particles called photons. The movement of photon causes heat. In a microwave oven, the photons collide with water molecules in the food and the food is warmed up.

Imagine two balls. one is fast moving and other is slow moving. When the fast one hit the slow ball, the energy is transfered from first to the latter. The slow ball gains energy due to impact and moves fast. The fast ball slows down due to loss of energy. There is a high probability of transferring energy from fast ball to slow ball and not vice versa.

It is the same case in heat energy also. That is why the thermodynamic laws says it is impossible to transfer heat from a body of low temperature to a body of high temperature.

Heat passage also indicates time passage. As a time flows, heat also flows. So temperature is also a measure of time.

Next time, when you feel the hot water, remember that the fast moving water molecules dash against your skin with vengeance.

Comments

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

sciencecapsules

Search This Blog