The law of conservation of energy is the first law of thermodynamics. It simply means a constant state of energy cannot be created or destroyed; it can only be shifted or transformed from one form to another. The energy can be transferred from one element or substance to another substance. For example, kinetic energy can be transferred to potential energy or chemical energy can be transferred into potential energy.
The mathematical equation of energy is as follows:
∆U= q + w
Delta means the change. Here, q and w are dependent on each other and can hold the charge on how the charge will be carried out. They are only dependent on the extent of the initial and final stage, out of this range, they are fully independent. If no change occurs or the transfer is 0, then the change will automatically be 0.
Principle of the law of conservation
The principle of the law of conservation of energy can simply be described as the conversion of one form of energy to another form of energy.
By using newton's second law of motion (F=ma), we can write the equation of energy conservation by using potential energy:
U(r2) – U(r1) = [T2-T1]
If we slightly shuffle the above equation, we get:
T2 + U(r2) = T1 + U(r1)
This rewritten equation shows that T+U is constant. The potential energy in both the equations is constant, and it will be constant even changing the equation back to one. This shows the law of conservation of energy that it can neither be destroyed nor created. It can, however, be transferred from one substance to another substance.
Heat and work energy
Heat and work energy are often used for the addition or subtraction of energy to form a new kind of energy, but the internal energy will remain unchanged.
Heat energy refers to the addition of energy by heating it, as the name clearly states. Work energy is the opposite of heat energy. Work-energy subtracts energy as a result of work.
It can be written as :
∆W = P dV
Here, P is the pressure,
DV is the change in the system.
After the transfer of heat, the heat energy can be written as:
∆Q = T dS
Here, T is the temperature,
dS is the change in the entropy.
Law of conservation for Class 11
The chapter on thermodynamics covers the concept of Specific Heat as a topic. The chapter as per the latest pattern covers a total of 8 marks. It consists of 1 short question, 2 very short questions, and one long question.
Illustrated Examples
Example 1) – Explain two types of primary reactions in chemical energy.
Answer – Exothermic and Endothermic Reactions.
Example 2) – Explain Endothermic reactions.
Answer – In the reaction, if the heat is absorbed, it’s called Exothermic.
Example 3) – Explain Exothermic reactions.
Answer - In the reaction, if the heat is produced, it’s called Exothermic.
FAQs on Law of Conservation of Energy
Q. What is the mathematical representation of Energy?
Q. How can you represent the heat of energy, after the transfer of heat, in an equation?
Q. Explain in short, the principle law of conservation?
Q. What’s the first law of thermodynamics?
Q. Can energy be destroyed or fused?
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