Energy Forms and Conservation

Energy Forms and Conversion

• Energy can be stored in matter (e.g., oil, gas, coal)
• Energy is a limited quantity and its total amount in the universe is constant
• Energy cannot be created or destroyed, but it is transformed from one form to another

Types of Energy

• Kinetic energy (Ek) = ½ mass x velocity squared
• Thermal energy (Heat) is a type of kinetic energy due to the movement of atoms
• Electrical energy is related to the molecules, atoms, and electrons within matter
• Nuclear energy is related to the center of the nucleus and is also known as atomic energy
• Potential energy is the energy expended to raise an object, affected by gravity

Energy Conversion

• Energy conversion efficiency is the ratio between the energy produced and the energy used
• Efficiency = energy produced / energy used
• Examples of energy conversion systems:
  • High efficiency: electric generator (dynamo) or water turbine (turbine)
  • Low efficiency: wind energy or electrical energy using coal, solar energy or internal combustion engines (car motor)

Energy Conversion Examples

• Converting kinetic wind energy into electrical or mechanical energy
• Converting chemical energy into thermal energy
• Converting solar energy into chemical energy through photosynthesis
• Converting kinetic energy into electrical energy to operate lamps

Energy and Temperature

• The speed of molecules increases with temperature, leading to a transfer of kinetic energy from warm to less warm matter
• Temperature is a measure of the average kinetic energy of molecules
• Zero degrees Celsius represents the complete static of molecular movement, corresponding to the freezing point of water
• 100 degrees Celsius represents the excessive movement of water molecules, corresponding to the boiling point of water

Potential Energy

• Potential energy is the energy expended to raise an object, affected by gravity
• When several thousand tons of water are lifted behind a dam, energy is stored in the water and is called stored energy
• The force of gravity to pull any body to the Earth is called the weight of the body
• Body weight = mass x acceleration due to gravity (mg)

Electrical Energy

• Electrical energy exists in several forms, including:
  • Chemical energy: the bonding of atoms and molecules by electrical forces
  • Electromagnetic energy: solar radiation in the form of waves that carry energy to the Earth
• Electromagnetic waves that carry energy include:
  • X-ray
  • Ultraviolet
  • Infrared
  • Microwaves
  • Radio waves

Nuclear Energy

• Nuclear energy is related to the center of the nucleus and is also known as atomic energy
• Nuclear energy technology is used for:
  • Military purposes (e.g., making an atomic bomb)
  • Peaceful purposes (e.g., generating electrical energy through a nuclear reactor)