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First law of thermodynamics

First law of thermodynamics

What is the first law of thermodynamics?

Many power plants and engines work by converting heat energy to work. This is due to the fact that the heated gas is able to operate and move mechanical turbines or pistons. The first law of thermodynamics applies the principle of conservation of energy. Accordingly, heat transfer and system work are the methods of transferring energy into and out of systems. The internal energy of a system according to the first law of thermodynamics Delta UQUdelta, U is the net heat transfer QQQ to the system and the sum of the net work (WWW) applied on the system. As the equation, the first law of thermodynamics is given as follows.

Δ U = Q + W

Here Delta U olanUdelta, the internal energy of the U system is the change in the UUU. QQQ is the net heat transferred to the system – that is, the QQQ is the net sum of all heat transfers entering and exiting the system. WWW is a net work on the system.

So, the added value of heat adds energy to the QQQ system, and the added value adds energy to the WWW system. For this reason, the first law takes the form of Delta U = Q + WtaU = Q + Wdelta, U, equals, Q, plus, W. This means that we can add internal energy by heating or heating a system.

What do these terms ( Delta U, Q, W QU, Q, Wdelta, U, comma, Q, comma, W) mean?

Nothing other than gas (air or helium) in a container with a moving but tightly plunger can be a better example of the first law of thermodynamics. We will accept that the piston can move up and down, that is, it can compress the gas or allow the gas to expand (but the gas cannot get out of the container).

The internal energy UUU of our system can be considered as the sum of the kinetic energies of each gas molecule. That is, if the temperature of the gas increases TTT, the gas molecules are accelerated and the internal energy of the gas increases the UUU (which means Delta U gazUdelta, U is marked with a plus). Similarly, if the temperature of the gas decreases, the gas molecules are slowed and the internal energy of the gas is reduced by the UUU (which means that the Delta is U veUdelta, U is marked as negative).
When the speed of gas molecules increases, it is important to remember that both internal energy (UUU) and temperature (TTT) increase. Because there are two methods to measure the same thing, which is how much energy is in the system. Because the temperature and the internal energy are proportional to each other, the temperature increases by two times when the internal energy increases by twice. Similarly, if the temperature does not change, the internal energy does not change.
One way to increase the internal energy UUU (and hence the temperature) of the gas is to transfer heat (QQQ) to the gas. We can do this by placing the container on a Bunsen burner or by dipping it into boiling water. The high temperature environment will pass the heat through the walls of the vessel to the gas and cause the gas molecules to move faster. If the heat enters the gas, the QQQ will be marked with a plus. On the contrary, we can reduce the internal energy of the gas by transferring heat out of the gas. We can do this by putting the container in an ice bath. If the heat exits the gas, QQQ will be a negative number.

Since the pistons are movable, they can work on the gas by moving downwards and compressing the gas. The collision of the piston and the gas molecules moving downwards allows the gas molecules to move faster and increase the total internal energy.

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