Energy

Energy is a property of matter and space.

• Can be transferred between objects
• Cannot be crated or destroy
• Can be used to heat, move or illuminate

Measures

$$1J=1Ws=1Nm=1kg\cdot m^2/s^{-2}$$

Joule

• Unit of energy

Watt

• Unit of power

Some approximations

• 1 kWh = 3 day of hiking
• 10kWh = 1l of diesel

Newton

• Unit of force
• Measure how much force is required to make 1kg accelerate 1m/s per second (1N=1kg·m/s²)
• On Earth, a mass of 1kg pushes on its support with an average force of 9.8N

Type of energy

• Chemical energy
• Sound energy
• Renewable energy
• Solar energy
• Nuclear energy
• Elastic energy
• Gravitational potential energy
• Kinetic energy
• Dark energy
• Hamiltonian mechanics
• Internal energy

For example:

1. human throws the stone using energy stored in muscles = chemical energy
2. stone moves upwards = kinetic energy
3. stone at the highest point = potential energy
4. stone falls to ground = kinetic energy
5. stone hits ground = thermal energy/sonic energy