Energy Chapter 4.1

Energy (4.1)

• Energy Stores: Energy exists in various forms.
  • Kinetic Energy: Energy of motion.
  • Gravitational Potential Energy: Energy due to height and gravity.
  • Elastic Potential Energy: Energy stored in stretched/compressed objects.
  • Thermal Energy: Energy related to temperature and particle motion.
  • Chemical Energy: Energy stored in chemical bonds.
  • Magnetic Energy: Energy stored in magnetic fields.
  • Electrostatic Energy: Energy stored in electric fields.
  • Nuclear Energy: Energy stored in the nucleus of atoms.
• Systems: A system is an object or group of objects considered for analysis. Energy can be transferred:
  • Into or out of the system.
  • Between objects within the system.
  • Between energy stores.
• Energy Transfers: Energy can be transferred mechanically, electrically, by heating, or by radiation.
• Power: Defines the rate at which energy is transferred or work is done.
  • Formula: Power (W) = Energy Transferred (J) / Time (s) or Work Done (J) / Time (s).
  • Unit: 1 Watt (W) = 1 Joule (J) per second. Higher power = faster energy transfer.
• Conservation of Energy: Energy cannot be created or destroyed, only transferred, stored, or dissipated.
• Dissipation of Energy: Useful energy is transferred. Wasted energy is lost as thermal energy to surroundings.
• Efficiency: Efficiency (percentage) = Useful Energy Transferred / Total Energy Supplied * 100.
• Reducing Energy Dissipation: Methods include insulation, lubrication, and streamlined designs.

National and Global Energy Resources

• Fossil Fuels (Coal, Oil, Natural Gas):
  • Reliable, high energy output.
  • Non-renewable, produces greenhouse gases.
• Nuclear Power:
  • High energy output, no greenhouse gas emissions during operation.
  • Non-renewable, produces radioactive waste.
• Renewable Resources: Sustainable, no greenhouse gases during operation; can be weather-dependent, high initial costs.
  • Examples: Solar, wind, hydroelectric, geothermal, tidal, biomass.

Waves (4.6)

• Waves: Transfer energy and information without transferring matter.
• Types of Waves:
  • Transverse Waves: Vibrations perpendicular to wave travel (e.g., light, water waves).
  • Longitudinal Waves: Vibrations parallel to wave travel (e.g., sound waves).
• Wave Properties:
  • Amplitude: Maximum displacement from rest.
  • Wavelength (λ): Distance between corresponding points on adjacent waves.
  • Frequency (f): Number of waves per second (Hertz).
  • Period (T): Time for one complete wave (T = 1/f).
  • Wave Speed (v): v = fλ.
• Electromagnetic Spectrum: Waves arranged by frequency (lowest to highest): Radio waves, Microwaves, Infrared, Visible light, Ultraviolet, X-rays, Gamma rays.
  • All EM waves travel at 3 x 10⁸ m/s in a vacuum. Higher frequency = more energy.
  • Uses and Dangers: Detailed information for each type of radiation (e.g., radio waves for communication, microwaves for cooking, ultraviolet for sterilization, potential dangers of X-rays and gamma rays).

Electricity (4.2)

• Current (I): Flow of electric charge (measured in amperes, A). I = Q/t (where Q = charge, t = time).
• Potential Difference (Voltage, V): Energy transferred per unit charge (measured in volts, V). V = W/Q (where W = work done).
• Resistance (R): Opposition to current (measured in ohms, Ω). V = IR (Ohm's Law).
• Series Circuits: Same current through all components, total resistance is the sum of individual resistances, potential difference is shared.
• Parallel Circuits: Current splits between branches, potential difference is the same across each branch, total resistance is less than the smallest resistance.

Space Physics (4.8)

• Solar System: Consists of the Sun, planets, moons, dwarf planets, asteroids, and comets.
• Red-Shift: Increase in wavelength of light from distant galaxies, appearing redder. Evidence of galaxies moving away, universe expanding, and supports the Big Bang theory.