1. Chapter 2.5 Energy Conversions

2. Evidence of Energy Conversions  Motion is most obvious  Change in position is evidence of gravitational potential energy  Change in shape is evidence an object has undergone a change in energy (elastic potential energy)  Change in temperature

3. Energy Conversions in Natural Systems  Hydrogen-hydrogen fusion in centre of the Sun  Photosynthesis converts light energy into chemical potential energy  Carbon dioxide + water + sun’s energy  glucose + oxygen  Cellular Respiration (Animals eating food)  Glucose + oxygen  carbon dioxide + water + energy (ATP and heat)  Fossil Fuel Combustion releases energy from chemical bonds

4. Energy Conversions in Technological Systems  Hydroelectric dams convert energy of moving water into electricity  See Fig 2.17 on Pg 192  Coal-burning power stations convert chemical energy into electricity  See Fig 2.18 on Pg 192

5. Nuclear Energy Conversions  CANDU (Canadian Deuterium Uranium) reactor is the most widely used nuclear reactor  Uranium is split with nuclear fission, releasing nuclear radiation. Eventually this energy is converted to electricity  See Fig 2.19 Pg 193  Thermal power stations use heat (coal- burning and nuclear power stations)

6. Solar Energy Conversions  Solar cells convert solar energy directly into electricity  Operates like a battery  See Fig 2.20 on Pg 194 (Read the description)

7. Fuel Cells  Operates like a battery  Converts chemical energy in fuel (hydrogen) into electrical energy. Does not need recharging because it will work as long as fuel is supplied.  Byproducts are water and heat.