P1.2 Using Energy

Energy transfer - Types of energy

1. Electicial

2. Light

3. Sound

4. Kinetic (Movement)

5. Nuclear

6. Thermal (Heat)

7. Gravitational Potential

8. Elastic Potential

9. Chemical

Energy transfer - Conservation of energy

1. All energy comes from the Sun

2. Energy cannot be created or destroyed

3. We can only transfer energy from one type into another

4. Energy is only useful when it can be transferred from one form to another

Examples of energy transfers:

Bunsen burner - Chemical (gas) to Heat and Light

Generator - Kinetic (wind) to Electric and Heat

Catapult - Elastic Potential to Kinetic and Heat

Efficiency formula

Energy  =  Useful Energy out

  Total Energy in

Example: A TV has an input energy of 220J. It gives out 5J of light energy, 2J of sound energy and 213J as heat energy. Work out the efficiency of the TV.

The light and sound energy are useful, but the heat energy is wasted, therefore:

Efficiency  =   5 + 2   =     7       =    0.0318   =  3.18%

                      220         220

• All appliances waste some energy
• This heat is transferred to cooler surroundings, which then become warmer
• As the heat is transferred to cooler surroundings, the energy dissipates - so it becomes less useful

Energy transfer - Sankey diagrams