alberta science 10 unit b3

Principles of Energy Conservation and Thermodynamics

Laws of Thermodynamics

• Key Focus: Advances in technology and their environmental impact.

• Terminology:

  • System: An interconnected set of parts involved in energy transfer or work (e.g., swing, ball-floor system).

  • Environment/Surrounding: Everything outside the system, not involved in the work.

  • Open System: Exchanges matter and energy with surroundings (e.g., Earth).

  • Closed System: Exchanges only energy, not matter (e.g., hot bowl of soup).

  • Isolated System: Exchanges neither matter nor energy (e.g., universe).

Definitions

• Heat: Transfer of thermal energy from one location to another (involved in the system).

• Work: Movement of matter from one location to another (involved in the system).

First Law of Thermodynamics

• Statement: Total energy in a system remains constant; also known as the Law of Conservation of Energy.

  • Heat added increases internal energy, leading to temperature rise and mechanical energy increase.

  • Examples:

    • Apple falling from a tree: Gravity acts downward, aligns with displacement.

    • Kicking a soccer ball: Force applied in direction of displacement.

    • Rubbing sticks together: Increases temperature indicates increased internal energy due to mechanical work.

Negative Work on the System

• Negative work occurs when the force acts opposite to the displacement, which decreases mechanical energy.

  • Examples:

    • Object thrown upwards, gravity does negative work (acts down while displacement is up).

    • Walking against friction, which is negative work on the system.

    • Sweating removes heat (evaporation absorbs body heat).

Perfect Machine

• Definition: Mechanical energy input equals mechanical energy output, theoretically 100% efficiency.

• Reality: No perfect machines exist; the goal is to improve efficiency.

Second Law of Thermodynamics

• Describes the direction of energy flow; heat always flows from hot to cold.

Heat Engines

• Definition: Devices converting forms of energy; specifically, heat engines convert thermal energy into mechanical work.

  • Types of Heat Engines:

    1. Internal Combustion Engine: Combustion occurs inside the cylinder, converting high-temperature heat into mechanical energy.

    2. External Combustion Engine: Combustion occurs outside (e.g., steam engine).

Heat Pump

• Moves thermal energy against spontaneous transfer; absorbs heat from cold space, releases it to warmer space.

• Applications: Refrigerators and air conditioners.

Historical Technological Development

• Innovations in simple technology (e.g., levers, wheels) to engines powered by horse labor transitioned to recognizing heat as energy.

  • Timeline of Breakthroughs:

    • 1680: Piston driven by internal energy (steam).

    • 1794: Transition from steam to gas energy sources.

Efficiency and Energy Consumption

• Most common energy sources: Solar, wind, hydroelectric, fossil fuels.

• Notable practices to reduce energy consumption include replacing incandescent bulbs with LEDs and reducing use of fossil fuels.

Environmental Impact and Future Technology

• Emissions from fossil fuels lead to global warming; reducing these emissions is critical.

• Sustainable society emphasizes meeting needs without impacting future generations.

• Cogeneration: Utilizing waste energy from one process to help power another, improving overall energy efficiency.

• Society's energy demands are increasing; it’s vital to search for alternative energy sources and improve efficiencies in existing technologies.

Summary of Useful Energy and Efficiency

• In any energy system, some energy converts to waste heat, reducing overall efficiency.

• Engineers continually develop technologies to minimize waste through better designs.

• Efficiency Formula:[ \text{Efficiency} (%) = \frac{\text{Useful Energy Output}}{\text{Energy Input}} \times 100 % ]

General Practices to Improve Efficiency

1. Choosing energy-efficient appliances.

2. Encouraging the use of public transportation.

3. Reevaluating energy sources utilized for power generation.

Principles of Energy Conservation and Thermodynamics

Laws of Thermodynamics

• Key Focus: Advances in technology and their environmental impact are crucial to understanding how energy systems operate and how they can be optimized for sustainability.

Terminology:

• System: An interconnected set of parts involved in energy transfer or work. Examples include a swing set and a ball-floor system, highlighting interactions between components and energy.

• Environment/Surrounding: Everything outside the system not involved in the work or energy transfer, including the air, surrounding structures, and other systems.

• Open System: A system that exchanges both matter and energy with its surroundings, exemplified by Earth, which receives solar energy and dissipates heat.

• Closed System: A system that exchanges energy but not matter with its surroundings. For instance, a hot bowl of soup retains its contents while losing heat to the air.

• Isolated System: A theoretical construct that exchanges neither matter nor energy, represented by the universe, which contains all forms of energy and matter in a balanced state.

Definitions:

• Heat: The transfer of thermal energy from one location to another. It can occur through conduction, convection, or radiation and is a critical aspect of energy systems.

• Work: The movement of matter from one location to another due to the application of force, integral to understanding energy dynamics within a system.

First Law of Thermodynamics

• Statement: The total energy in a closed system remains constant; it is also known as the Law of Conservation of Energy. Energy can neither be created nor destroyed, only transformed from one form to another.

• Effects of Heat Addition: Adding heat to a system increases its internal energy, resulting in a rise in temperature and an increase in mechanical energy available for work.

Examples:

• Apple Falling: As an apple falls from a tree, gravitational force acts downward, correlating with the displacement and converting gravitational potential energy to kinetic energy.

• Kicking a Soccer Ball: The force applied by the foot in the direction of the ball’s displacement exemplifies direct work done on the system.

• Rubbing Sticks Together: Frictional forces create heat, indicating increased internal energy due to mechanical work and showcasing energy transformations.

Negative Work on the System

• Negative Work: This occurs when the force acts in the opposite direction of the displacement, leading to a decrease in the system's mechanical energy.

Examples:

• Object Thrown Upwards: When an object is thrown upwards, gravity performs negative work because it acts downward while the object's displacement is upward.

• Walking Against Friction: Moving against friction requires energy to overcome resistance, resulting in negative work performed on the system.

• Sweating: Evaporation during sweating removes heat from the body, illustrating how the body does work to cool itself through heat loss.

Perfect Machine

• Definition: A perfect machine is one where mechanical energy input equals mechanical energy output, theoretically achieving 100% efficiency.

• Reality Check: In practice, no perfect machines exist due to energy losses, primarily as waste heat, making the goal of improving efficiency vital in engineering applications.

Second Law of Thermodynamics

• Describes the directional flow of energy; specifically, heat naturally flows from regions of high temperature to regions of low temperature, contributing to the concept of entropy in systems.

Heat Engines

• Definition: Devices that convert various forms of energy into useful mechanical work, specifically thermal energy into mechanical energy, showcasing real-world applications of thermodynamics.

Types of Heat Engines:

• Internal Combustion Engine: Combustion occurs within the cylinder, using high-temperature gases to produce mechanical energy by forcing down a piston.

• External Combustion Engine: Combustion occurs outside the engine (e.g., steam engines), where steam generated from heated water pushes a piston.

Heat Pump

• Purpose: Moves thermal energy against its natural direction of flow; it absorbs heat from a colder space and releases it to a warmer space.

• Applications: Commonly found in refrigerators and air conditioners, which are essential for maintaining comfort in living and working environments.

Historical Technological Development

• Innovations progressed from simple tools like levers and wheels to complex machines powered by horse labor, eventually leading to the recognition of heat as a fundamental form of energy.

• Timeline of Breakthroughs:

  • 1680: Development of the piston driven by internal energy in steam engines changed the landscape of energy use.

  • 1794: The transition from steam to gas energy sources marked a significant turning point in energy production and efficiency.

Efficiency and Energy Consumption

• Common Energy Sources: The most prevalent sources of energy today include solar, wind, hydroelectric, and fossil fuels. Each has unique environmental footprints and efficiencies.

• Notable Practices: To reduce energy consumption, practices such as replacing incandescent bulbs with energy-efficient LEDs and decreasing reliance on fossil fuels play a critical role in promoting sustainability.

Environmental Impact and Future Technology

• The emissions produced by burning fossil fuels contribute significantly to global warming, making the reduction of these emissions crucial for a sustainable future.

• A sustainable society aims to meet current needs without compromising future generations' ability to meet their needs, necessitating a shift toward renewable energy sources and enhanced energy efficiency.

• Cogeneration: The process of capturing waste energy from one system to power another enhances overall energy efficiency by maximizing energy use.

• Given the increasing energy demands of society, finding alternative energy sources and improving the efficiency of existing technologies is imperative to mitigate environmental impacts.

Summary of Useful Energy and Efficiency

• In every energy system, some energy typically converts to waste heat, which reduces overall efficiency. Understanding this loss is critical for improving energy systems.

• Engineers' Role: Continuous development of technologies aims to minimize waste energy through improved designs and innovative approaches to energy use.

Efficiency Formula:

• Combating energy waste is essential for optimizing operations and practices that utilize energy effectively. The formula for efficiency is expressed as:

[ \text{Efficiency} (%) = \frac{\text{Useful Energy Output}}{\text{Energy Input}} \times 100 % ]

General Practices to Improve Efficiency

• Choosing energy-efficient appliances not only conserves energy but also reduces overall energy bills.

• Encouraging the use of public transportation as a way to decrease individual vehicular energy consumption.

• Reevaluating and transitioning to cleaner, renewable energy sources for power generation is essential to driving systemic change in energy efficiency and sustainability.