The Physics of Energy: Chapter 1

Conservation of Energy: - energy is never lost, only converted - energy does not change with time - when people say energy has been consumed, they mean it’s been degraded to a less useful state

Matter = Energy - matter is a form of energy - mass contains energy but it’s impossible to extract and use with any foreseeable technology

I wonder if there’s a way to directly convert mass to energy without using antimatter? We could harness all the mass energy on Earth. Or even if we could somehow create antimatter.


Fundamental Unit of Energy: 1 Joule = \(1 kgm^2/s^2\)

Unit of Force: Newtons 1 Newton = \(1kg m/s^2\)

Work: Multiplying force along a distance.

Power: Rate at which energy is used, measured in watts 1 W = 1 J/s

KwH: 1KwH = 1KW x 36000s = 3.6MJ

Pressure \[P = F/A = m/d \cdot t^2\] Unit: Pascals (Pa) \[1 Pa = 1 N/m^2\]

Forms of Energy

Each form of energy can be converted into every other form of energy.

Mechanical and Kinetic Energy - KE of an object of mass m moving at speed v \[KE = \frac{1}{2}mv^2\]

Thermal Energy - Contained in the microscopic dynamics of a large number of molecules, atoms or other constituents - The thermal energy of air would include KE + energy of the vibrations in the air

Electromagnetic Energy - one of the four fundamental forces of nature - Electrically charged particles produce electric and magnetic fields that exert forces on other charged particles

Chemical Energy - energy stored in chemical energy bonds within a material - e.g the chemical energy stored in the carbon bonds in an apple is released when someone can eat it and then can walk - energy in a chemical bond can be measured in electron volts (eV) - 1eV is the energy needed to move a single electron across a one volt electric potential difference \[1ev = 1.602 18 x 10^{-18}\] - standard unit of energy is the calories (Cal)

Nuclear binding energy - short range force that binds the nucleons in a nuclei together

Mass Energy - mass is a form of energy - each particle is an excitation of a quantum field e.g single photon is an excitation of electromagnetic field - its difficult to convert mass energy into a useful form - can be done by using an antiparticle to annihilate the particle and release if the mass energy as electromagnetic radiation and/or kinetic energy - antimatter is not found naturally in the solar system \[E=mc^2\]

Final Thoughts:

Energy is everywhere - it’s matter of converting it into useable forms efficiently. Kardasheve Scale measures types of civilizations by our ability to extract energy from different sources. –> Civilization 1: can harness all energy on earth given by our planet star. Read more here