Grade 10
  1. Mechanics  1.1. Dynamics  1.1.1. Motion in one dimension  1.1.2. Motion in two dimensions  1.1.3. Displacement and Distance  1.1.4. Speed and Velocity  1.1.5. Acceleration  1.1.6. Graphical representation of motion  1.1.7. Equations of motion  1.1.8. Free fall and acceleration due to gravity  1.1.9. Projectile motion  1.1.10. Relative speed  1.2. Dynamics  1.2.1. Newton's Laws of Motion  1.2.2. Inertia and mass  1.2.3. Force and its types  1.2.4. action and reaction force  1.2.5. Friction and its effects  1.2.6. Coefficient of friction  1.2.7. Circular motion  1.2.8. Centripetal force and centripetal acceleration  1.2.9. Momentum and Impulse  1.2.10. Conservation of momentum  1.2.11. Newton's third law and applications  1.3. Work, Energy and Power  1.3.1. Work done by the force  1.3.2. Work–energy theorem  1.3.3. Kinetic energy  1.3.4. Potential energy  1.3.5. Mechanical energy  1.3.6. Energy Conservation  1.3.7. Power and efficiency  1.3.8. Renewable and non-renewable energy sources  1.4. Gravitational force  1.4.1. Newton's law of universal gravitation  1.4.2. Gravitational field and field strength  1.4.3. Acceleration due to gravity on different planets  1.4.4. Kepler's laws of planetary motion  1.4.5. Orbits and satellites  1.4.6. Weight and apparent weight  1.4.7. Gravitational potential energy
  2. Properties of matter  2.1. States of matter  2.1.1. Solid, liquid and gas  2.1.2. Molecular structure of matter  2.1.3. Intermolecular forces  2.1.4. Plasma and Bose–Einstein condensate  2.2. Pressure  2.2.1. Definition of Pressure  2.2.2. Pressure in liquids  2.2.3. Atmospheric pressure  2.2.4. Pascal's principle  2.2.5. Archimedes' Principle and Buoyancy  2.2.6. Surface tension and capillarity  2.3. Elasticity  2.3.1. Hooke's law  2.3.2. Stress and strain  2.3.3. Elastic Limit and Modulus of Elasticity  2.3.4. Applications of Elasticity
  3. Thermal physics  3.1. heat and temperature  3.1.1. Difference Between Heat and Temperature  3.1.2. Temperature scale  3.1.3. Thermal expansion  3.1.4. Thermal equilibrium  3.2. Heat transfer  3.2.1. Conductivity  3.2.2. Convection  3.2.3. Radiation  3.2.4. Insulation and its applications  3.3. Thermal properties of matter  3.3.1. Specific heat capacity  3.3.2. Latent heat and phase change  3.3.3. Boiling and Melting Point  3.3.4. Heat engines and refrigeration  3.4. Laws of Thermodynamics  3.4.1. Zeroth law of thermodynamics  3.4.2. First law of thermodynamics  3.4.3. Second law of thermodynamics  3.4.4. Carnot cycle
  4. Waves and optics  4.1. Nature and properties of waves  4.1.1. Types of waves in nature and properties of waves  4.1.2. Transverse and longitudinal waves  4.1.3. Wave parameters  4.1.4. Reflection and refraction of waves  4.1.5. Superposition and Interference  4.1.6. Standing Waves and Resonance  4.1.7. Doppler effect  4.2. Sound waves  4.2.1. Characteristics of sound waves  4.2.2. Speed of sound in different mediums  4.2.3. Applications of sound waves  4.2.4. Ultrasound and its uses  4.3. Light Waves and Optics  4.3.1. Nature of light  4.3.2. Reflection of light  4.3.3. Laws of reflection  4.3.4. Mirrors and Image Formation  4.3.5. Refraction of light  4.3.6. Snell's Law  4.3.7. Lenses and Image Formation  4.3.8. Total internal reflection and critical angle  4.3.9. Optical fibre  4.4. Optical Instruments  4.4.1. Microscope  4.4.2. Telescope  4.4.3. Human eye and vision defects  4.4.4. Camera and its working principle
  5. Electricity and Magnetism  5.1. Electrostatics  5.1.1. Electric charge and its properties  5.1.2. Conductors and Insulators  5.1.3. Coulomb's law  5.1.4. Electric field and field lines  5.1.5. Electric potential and potential difference  5.1.6. Capacitors and Capacitance  5.2. Current Electricity  5.2.1. Electric current and its measurement  5.2.2. Ohm's law  5.2.3. Resistance and resistivity  5.2.4. Series and Parallel Circuits  5.2.5. Electric power and energy  5.2.6. Kirchhoff's Laws  5.3. Magnetism and Electromagnetism  5.3.1. Magnetic field and field lines  5.3.2. Magnetic effects of electric current  5.3.3. Electromagnetic induction  5.3.4. Faraday's laws of electromagnetic induction  5.3.5. Transformers and Applications  5.3.6. AC and DC current
  6. Modern Physics  6.1. Nuclear physics  6.1.1. Structure of the atom  6.1.2. Bohr's atomic model  6.1.3. Electron Energy Levels  6.1.4. X-rays and applications  6.2. Radioactivity  6.2.1. Types of radiation  6.2.2. Half-life and radioactive decay  6.2.3. Nuclear reactions and applications  6.2.4. Fission and Fusion  6.3. Quantum physics  6.3.1. Wave–particle duality  6.3.2. Photoelectric effect  6.3.3. Energy quantization  6.3.4. Heisenberg's uncertainty principle
  7. Electronics and Communication  7.1. Semiconductors  7.1.1. Conductors, Insulators and Semiconductors  7.1.2. Diodes and their applications  7.1.3. Transistors and Logic Gates  7.1.4. LEDs and photodiodes  7.2. Communication Systems  7.2.1. Basics of communication  7.2.2. Analog and digital signals  7.2.3. Wireless and optical fibre communication  7.2.4. Radio Waves and Modulation

Grade 10 → Mechanics → Work, Energy and Power ↓


Energy Conservation


The principle of conservation of energy is a fundamental concept in physics. It states that energy in an isolated system cannot be created or destroyed; it can only be converted from one form to another. The total amount of energy in a closed system remains constant over time. This principle is called the "law of conservation of energy" and is a cornerstone of physics as it applies to processes occurring in the universe.

Understanding energy

Before we discuss the principle of conservation of energy, it is important to understand what energy is. Energy is the capacity to do work. In physics, work is done when a force is applied to an object, and the object moves in the direction of the force. The standard unit of energy is the joule.

Energy comes in different forms, and it can be converted from one form to another. Some common forms of energy are:

  • Kinetic Energy: Energy produced by the motion of an object.
  • Potential Energy: Energy stored in an object due to its position or configuration.
  • Thermal energy: The internal energy in substances; it is the vibration and movement of atoms and molecules within substances.
  • Chemical Energy: Potential energy stored in the chemical bonds of molecules.
  • Electrical Energy: Energy produced by the flow of electric charge.
  • Sound Energy: Energy carried by sound waves.
  • Light Energy: Energy carried by electromagnetic waves.

Kinetic and potential energy

Kinetic energy

Kinetic energy (( KE )) is the energy of motion. Any moving object possesses kinetic energy. The formula to calculate kinetic energy is:

KE = 0.5 * m * v^2

Where ( m ) is the mass of the object and ( v ) is the velocity of the object.

V object

Potential energy

Potential energy (( PE )) is the stored energy of an object's position. One of the common types of potential energy is gravitational potential energy. It can be calculated using:

PE = m * g * h

Where ( m ) is the mass, ( g ) is the acceleration due to gravity (9.8 m/s² on Earth), and ( h ) is the height above the reference point.

H object

Law of conservation of energy

The law of conservation of energy states:

"Energy cannot be created or destroyed; it can only be transformed from one form to another. The total energy of an isolated system remains constant."

This means that the energy in a closed system must always be the same, but it can move between different types of energy. Real-world examples help to understand this principle.

Real examples of energy conservation

Example 1: Swing

Imagine a child playing on a swing. At the highest point of motion, the swing has maximum potential energy and minimum kinetic energy because its speed is zero. Conversely, at the lowest point, the swing has maximum kinetic energy and minimum potential energy. The total mechanical energy remains constant, provided that air resistance and friction are negligible.

This relationship can be represented as follows:

PE_{top} = KE_{bottom} + PE_{bottom}

Example 2: Roller coaster

A roller coaster at the top of a hill has maximum potential energy due to its height. As it descends, this potential energy turns into kinetic energy as it gains speed. At the bottom of the hill, the potential energy is minimal, and the kinetic energy is maximum. As the coaster climbs another hill, the kinetic energy turns back into potential energy.

Start Top Ending

Mathematical representation

To describe the conservation of mechanical energy mathematically:

E_{total} = KE + PE

Where:

  • (E_{total}) is the total mechanical energy
  • (KE) is the kinetic energy
  • (PE) is the potential energy

For any two states in a system where there is a conservative conversion of energy:

KE_1 + PE_1 = KE_2 + PE_2

Practical implications and energy losses

In practical situations, perfect energy conservation (where no energy is lost) is rare. Some energy is converted into other forms of thermal energy due to friction. However, even in these cases, the total energy—when all forms are included—is conserved.

For example, when you ride a bicycle, the chemical energy released from your muscles is converted into kinetic energy. Some of it is converted into thermal energy and some into sound energy due to the friction between the bicycle tyres and the road.

Conclusion

Conservation of energy is an important principle in understanding physics. Knowing that energy is not destroyed but changes form helps us understand and predict the behavior of various systems. This applies in a variety of scenarios, from everyday activities to the complex workings of machines and the universe. With this knowledge, engineering solutions, technology innovation, and scientific understanding continue to advance.


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Energy Conservation

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