# 11 Lecture

## Conservation of Energy

Conservation of energy is one of the fundamental principles of physics. It is a concept that refers to the idea that energy cannot be created or destroyed, only transformed from one form to another.

## Important Mcq's Midterm & Finalterm Prepration Past papers included

What is the law of conservation of energy?

Answer: The law of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed from one form to another.

Explain the difference between kinetic and potential energy.

Answer: Kinetic energy is the energy possessed by a moving object while potential energy is the energy possessed by an object due to its position or configuration.

Can energy be completely conserved in a real-world situation?

Answer: Energy cannot be completely conserved in a real-world situation due to the presence of various energy losses such as friction, air resistance, and heat.

What is the principle of work-energy theorem?

Answer: The principle of the work-energy theorem states that the net work done on an object is equal to the change in its kinetic energy.

What is elastic potential energy?

Answer: Elastic potential energy is the potential energy stored in an elastic material when it is stretched or compressed.

Give an example of a non-conservative force.

Answer: Friction is an example of a non-conservative force as it dissipates energy in the form of heat and sound.

Why is mechanical energy conserved in an isolated system?

Answer: Mechanical energy is conserved in an isolated system because no external work is done on the system, and there are no energy losses due to non-conservative forces.

What is the relationship between potential energy and conservative forces?

Answer: Potential energy is associated with conservative forces as they depend on the position or configuration of an object in a force field.

Can the total energy of a system be negative?

Answer: No, the total energy of a system cannot be negative as energy is always a positive quantity.

How can the conservation of energy be applied to solve real-world problems?

Answer: Conservation of energy can be used to analyze and solve real-world problems involving energy transfer and transformation. By applying the principle of conservation of energy, one can determine the initial and final energies of a system and calculate the work done or energy transferred in a given process.

## Subjective Short Notes Midterm & Finalterm Prepration Past papers included

What is the law of conservation of energy?

Ans: The law of conservation of energy is a fundamental principle of physics that states that the total amount of energy in a closed system remains constant.

What is the first law of thermodynamics?

Ans: The first law of thermodynamics states that the change in the internal energy of a system is equal to the heat added to the system minus the work done by the system.

What are some applications of the conservation of energy in physics?

Ans: Conservation of energy has many applications in physics, including mechanics, thermodynamics, and electromagnetism.

How is conservation of energy used in the design of engines?

Ans: In the design of engines and other devices that convert thermal energy into mechanical work, the principle of conservation of energy is used to ensure that the heat energy added to the system is equal to the work done by the system.

How does conservation of energy apply to electromagnetism?

Ans: In electromagnetism, the energy stored in a magnetic field is equal to the work that can be done by the field. When the current is turned off, the energy stored in the magnetic field is released and can be used to do work.

Is energy created or destroyed in a closed system?

Ans: Energy cannot be created or destroyed in a closed system, only transformed from one form to another.

What happens to the potential energy of an object as it falls?

Ans: The potential energy

### Conservation of Energy

Conservation of energy is one of the fundamental principles of physics. It is a concept that refers to the idea that energy cannot be created or destroyed, only transformed from one form to another. In other words, the total amount of energy in a closed system remains constant. This principle has significant implications in various areas of physics, including mechanics, thermodynamics, and electromagnetism. The law of conservation of energy is based on the first law of thermodynamics, which states that the change in the internal energy of a system is equal to the heat added to the system minus the work done by the system. In other words, energy cannot be created or destroyed, only transformed from one form to another. This means that the total amount of energy in a closed system remains constant. The principle of conservation of energy has many applications in physics. For example, it can be used to explain the behavior of objects moving under the influence of gravity. When an object is dropped from a height, its potential energy is converted into kinetic energy as it falls. When it reaches the ground, all of its potential energy has been converted into kinetic energy, and the total amount of energy in the system remains constant. Conservation of energy also has applications in thermodynamics, which is the study of heat and temperature. In a closed system, the total amount of energy remains constant, which means that the heat energy added to the system must be equal to the work done by the system. This principle is used in the design of engines and other devices that convert thermal energy into mechanical work. Another important application of the conservation of energy is in electromagnetism. When an electric current flows through a wire, it creates a magnetic field. This magnetic field has the potential to do work, and this work is equal to the amount of energy stored in the magnetic field. When the current is turned off, the energy stored in the magnetic field is released, and this energy can be used to do work. In summary, the law of conservation of energy is a fundamental principle of physics that states that the total amount of energy in a closed system remains constant. This principle has many applications in physics, including mechanics, thermodynamics, and electromagnetism. It is a powerful tool that allows scientists to explain the behavior of objects and systems and design new devices and technologies.