Physics: Law of Conservation of Energy

Law of Conservation of Energy

Definition

• The law of conservation of energy states that the total energy of an isolated system remains constant over time.
• Energy cannot be created or destroyed, only converted from one form to another.

Key Principles

• The total energy of a closed system is constant.
• Energy can change forms, but the total energy remains the same.
• There is no net gain or loss of energy.

Types of Energy

• Kinetic energy: energy of motion
• Potential energy: energy of position or stored energy
• Thermal energy: energy of heat
• Electrical energy: energy of moving charges
• Chemical energy: energy stored in chemical bonds
• Nuclear energy: energy stored in atomic nuclei

Examples

• A rolling ball converts kinetic energy to potential energy as it rolls uphill.
• A battery converts chemical energy to electrical energy.
• A generator converts mechanical energy to electrical energy.

Importance

• The law of conservation of energy is a fundamental principle in physics and engineering.
• It helps us understand and analyze energy transformations in various systems.
• It has numerous applications in fields such as energy production, transportation, and architecture.

Mathematically

• The law of conservation of energy can be mathematically represented as:

ΔE = Q - W

• ΔE: change in energy
• Q: heat added to the system
• W: work done on the system

Law of Conservation of Energy

• The law states that the total energy of an isolated system remains constant over time, and energy cannot be created or destroyed, only converted from one form to another.

Key Principles

• The total energy of a closed system is constant, and energy can change forms, but the total energy remains the same.
• There is no net gain or loss of energy, only conversions from one form to another.

Types of Energy

• Kinetic energy is the energy of motion.
• Potential energy is the energy of position or stored energy.
• Thermal energy is the energy of heat.
• Electrical energy is the energy of moving charges.
• Chemical energy is the energy stored in chemical bonds.
• Nuclear energy is the energy stored in atomic nuclei.

Examples of Energy Conversion

• A rolling ball converts kinetic energy to potential energy as it rolls uphill.
• A battery converts chemical energy to electrical energy.
• A generator converts mechanical energy to electrical energy.

Importance of the Law

• The law of conservation of energy is a fundamental principle in physics and engineering.
• It helps us understand and analyze energy transformations in various systems.
• It has numerous applications in fields such as energy production, transportation, and architecture.

Mathematical Representation

• The law of conservation of energy can be mathematically represented as: ΔE = Q - W.
• ΔE represents the change in energy.
• Q represents the heat added to the system.
• W represents the work done on the system.

Thermodynamics and Heat

• Internal Energy (U) is the total energy of a system, including kinetic energy, potential energy, and potential energy associated with molecular interactions.
• Heat (Q) is the energy transferred between bodies due to a temperature difference.

Laws of Thermodynamics

• Zeroth Law of Thermodynamics states that if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.
• First Law of Thermodynamics states that energy cannot be created or destroyed, only converted from one form to another, and is represented by the equation ΔU = Q - W.
• Second Law of Thermodynamics states that the total entropy of an isolated system always increases over time, and is represented by the equation ΔS = ΔQ / T.

Work (W)

• Mechanical Work is the energy transferred through a force applied over a distance, and is represented by the equation W = F * d.
• PV Work is the work done by a system during expansion or compression, and is represented by the equation W = ∫PdV.
• Isothermal Process is a process that occurs at constant temperature, with no change in internal energy (ΔU = 0).

Thermodynamic Processes

• Isochoric Process is a process that occurs at constant volume, with no change in volume (ΔV = 0).
• Adiabatic Process is a process that occurs with no heat transfer, resulting in a change in temperature (ΔT ≠ 0).
• Cyclic Process is a process that returns to its initial state, with no net change in internal energy (ΔU = 0).