Thermodynamics is the branch of Physics that deals with the relationship of energy to heat, work, and temperature, as well as the physical properties of matter and radiation. In other words, thermodynamics discusses how heat energy is converted into other forms of energy and how this process affects matter. A clear understanding of energy is required before moving on to the principles of thermodynamics.
Energy was once a mysterious concept. Scientists came up with a definition of energy after an in-depth study of heat, light, and mechanics. According to US Energy Information Administration (EIA), energy is the ability to do work. That is, energy is the ability to apply force over a given distance. Since the formulation of that concept, studies on the systematic properties of energy have accelerated. The laws that explained the nature of energy in all situations were discovered thereafter. We call these the laws of thermodynamics.
According to the book, William Thomson and Creation of Thermodynamics written by Crosbie W. Smith, William Thomson’s famous series of papers On the Dynamical Theory of Heat published between 851 and 1855 was essentially a development of the two laws of thermodynamics in mathematical-physical language. The First Law of Thermodynamics states that the total amount of energy in a closed system is constant, though energy can take many forms and change from one to another.
Energy - It’s many forms
Work is the force exerted over a distance. Energy is the feature of a physical system that enables it to exert force.
Let us see how force can be applied over a distance, or in what forms the energy can exist. When we throw an object, the energy gained by that object due to motion is called kinetic energy. A ball when thrown can shatter windowpanes and light bulbs. The kinetic energy makes this possible.
Another form of energy is potential energy. You can store potential energy. It is the energy that is waiting to be used. The water stored in a dam, the spring, and the battery in the torch are all examples of stored energy. All of these have the ability to apply force over a distance.
Next, we come to the various waveforms of energy. There is energy in different types of waveforms. There is energy in the sound waves that travel through the air, the waves of the oceans, and the seismic waves that cause earthquakes. These different waves carry energy through air, water, and solids.
Heat is also a form of energy. You can heat air; it will then expand. Water can be heated; it will boil. In these cases too, heat has applied force over a certain distance.
Light is another form of energy. Light is the form of energy that reaches us from the Sun. Light travels through the emptiness of space at a speed of 186,000 miles per second. Light energy is what gives plants the energy to grow. All living things depend on the energy from the sun in one way or another.
Under special circumstances, matter can also transform into energy. The energy from matter is converted into electric energy for human-made purposes.
Characteristics of energy
According to the article, ‘The Evolution of the Universe’ published in the Scientific American, for the past four centuries, scientists have believed that the universe has an underlying order. The conviction that matter cannot be created or destroyed is an extension of this. Under normal conditions, atoms do not simply form nor disappear, just like that. When a measure like mass does not change, physicists call it the Law of Conservation of Energy. In a closed system, the amount of matter is conserved.
What is system? It is one of the most important ideas in science. A system is like a box containing matter and energy. In Science, we always talk about system. We use the word system to refer to only a specific part of the vast universe. The Solar System is the biggest example of this. All objects that are attracted to the sun by gravity – such as planets, moons, comets, and asteroids – belong to the solar system. Earth is another system that is a part of the vast solar system.
The atoms we had in our body when we were born will not be the same as those present in our body when we reach middle age.
If we look at our bodies, we can see many systems – the digestive system, circulatory system, nervous system, and so on. We also know about different types of ecosystems.
There are open systems and closed systems. An open system is one in which matter and energy can flow in and out. Our body is an open system. This is because our body constantly exchanges matter and energy with its surroundings. Our body is always exchanging atoms with the environment. The atoms we had in our body when we were born will not be the same as those present in our body when we reach middle age.
A closed system is one in which matter or energy can never be added or removed. In fact, such a system cannot exist in nature. No system can stop the flow of energy.
Natural systems are often viewed as closed. For example, the current atoms on earth are the same as those at the time of earth’s formation. Comets and asteroids reach Earth from space, but they are very nominal compared to the regular atoms here. Matter is conserved in a closed system. Matter cannot be made or destroyed there.
Conservation of energy
After the study of various forms of energy, scientists began to doubt whether energy was being conserved or not; but verifying it was a dilemma to them. For that, we first need a clear understanding of the transformations and the properties of energy. This is exactly what the 19th century scientists tried.
We can observe in our everyday the transformations and properties of energy in the many energy-transfers that occur in nature. Let us examine the energy changes that occur when a roller coaster machine is running. As the roller coaster starts to rise slowly, the electric motor converts the electrical potential energy into kinetic energy and then into gravitational potential energy. Later, when it reaches its highest point, the gravitational potential energy peaks, and the kinetic energy decreases. Then, as it moves downwards, the gravitational potential energy is converted into kinetic energy. This kinetic energy also transforms into some other forms The noise and heat generated by the friction between the metals and the wind generated by the rapid movement of the coaster are all transformations of the kinetic energy here.
One of the major challenges faced by modern technology is the perpetual need to find ways to transform energy efficiently, from one form to another, at a low cost.
A ball bouncing up and down on the ground undergoes various forms of energy transformation, before it finally rests. When the ball is lifted, it attains gravitational potential energy, and when it falls to the ground, it is converted into kinetic energy. When it reaches the floor, it attains elastic potential energy. When it comes to a halt on the floor, it may raise the question as to where the energy has gone. Each time the ball hits the floor and bounces up, some kinetic energy is converted into heat. When the ball finally comes to a standstill on the floor, the ball and the floor on which it falls, would have attained slight degrees of heat. It may not be significant enough to be measured.
Vehicles are the biggest examples that illustrate the phenomenon of transformation of energy, in our everyday. Stored fuel in vehicles is a form of chemical energy. That energy is converted into heat in the engine, and the heat is then converted into kinetic energy, through the driving shaft which eventually causes movement in the vehicle.
One of the major challenges faced by modern technology is the perpetual need to find ways to transform energy efficiently, from one form to another, at a low cost. Power plants convert the chemical-potential energy of coal, the gravitational potential energy of water stored in dams, the kinetic energy of wind, and the nuclear energy of matter, into electricity. The more efficient a power plant is in transforming energy, the lower the price we have to pay for electricity.
Take the case of household appliances. If the fan that converts electrical potential energy into kinetic energy, the radio that converts electrical to sound energy, and the oven that converts electrical to thermal energy all become more energy-efficient, we would need to only spend a lesser amount of money on the electricity bill.
The search for ways to transform one form of energy into another form more efficiently is an ongoing quest in scientific research. Thermodynamics and its principles thus is vital to the quality of our existence on this planet.
Now put on your thinking hats and think about the following questions for a couple of minutes.
How would you describe the term “thermodynamics” to your students?
Can you think of the significance of thermodynamics in our everyday life?
Write down your thoughts and discuss them with your students, children and your colleagues. Listen to their views and compare them with your own. As you listen to others, note how similar or different your views are to others’.
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Thermodynamics and our Everyday