Types of Energy

  1. Chemical potential energy (in food, batteries and dynamite)
  2. Elastic potential energy (in rubber bands and springs)
  3. Gravitational potential energy (of objects some height above the ground)

Gravitational Potential Energy

GPE (joules) = Mass (kg) × Gravitational Acceleration (9.8 m/s2) × Height (m)
= m × g × h

A. GPE = m × g × h
= 2 kg × 9.8 m/s2 × 3 m
= 58.8 J (joules)

Kinetic Energy

KE (joules) = 12 Mass (kg) × Velocity2 (m/s)
= 12 m × v2
= 12 mv2

A. KE= 12 m × v2
= 12 × 2 kg × 10 m/s × 10 m/s
= 100 J

Nuclear Energy

Alpha rays (α) Helium nuclei 5% of the speed of light Low
Beta rays (β) Electrons Up to 90% of the speed of light Moderate
Gamma rays (γ) Electromagnetic waves Speed of light High

  1. Nuclear Fusion - involves the 'joining' of small nuclei (e.g. hydrogen) to make one larger nucleus (e.g. helium). This occurs in stars. Once the reaction is started, it creates sufficient energy to keep going.
  2. Nuclear Fission - This nuclear reaction involves the 'splitting' of one large unstable nucleus into two smaller stable nuclei. A minimum amount (critical mass) of radioactive material such as Uranium-235 is needed to start the fission reaction. The extra neutrons released collide with more large nuclei splitting them in turn. This is called a chain reaction. If uncontrolled, the chain reaction creates a bomb. To control the fission reaction, control rods and moderators in nuclear reactors absorb the extra neutrons so that a 'melt-down' does not occur.
Polonium-215 0.0018 seconds
Iron-59 46.3 days
Carbon-14 5930 years
Uranium-235 710 million years

Law of Conservation of Energy

Energy Transformations

  1. Light bulb
  2. Electrical Energy Arrow Light Energy + Heat Energy
  3. Car Battery
  4. Chemical Potential Energy Arrow Electrical Energy

Energy Transfers