P3

types of energy:

  • chemical energy- food, batteries and fuel

  • kinetic energy- moving objects.

  • thermal energy- hot objects

  • strain/elastic potential energy- stretched, squashed or twisted material.

  • GPE/gravitational potential energy= objects in high places or positions

  • atomic/nuclear energy= in atoms

-law of conservation of energy= energy cannot be created or destroyed.kai

-unit for measuring energy= J (joules)

-energy diagrams=

  • flow-

  • Sankey-

- Energy dissipates (spreads out) and then cannot be used as useful energy therefore becoming wasted.

-friction can be reduced by lubrication

-Efficiency- how good a machine is, always said between 0 and 1, given in percentage too.

-FORMULA FOR EFFICIENCY=

-insulation slows down the rate of energy with is transferred out the house by heating.

-ways in which energy can be transferred:

  • in conduction- metals are good thermal conductors

  • in convection- fluid that is warmer than the rest rises and sets up a convection current.

  • in radiation- the only way in which energy can be transferred through a vacuum. infrared can be absorbed and emitted easily by dull and dark surfaces while is absorbed and emitted poorly by light and shiny surfaces.

-air cannot form convection currents when trapped

-rate of which energy transfers depend on:

  • thickness

  • thermal conductivity

  • temperature difference across

-rate of energy transfer decreases by:

  • increased thickness

  • decreasing thermal conductivity

  • decreasing temperature difference

-when an object moves higher, the GPE of it increases

-FORMULA OF GPE=

-TRIANGLE FOR FORMULA OF GPE=

-FORMULA OF KINETIC ENERGY=

-non-renewable energy means that they will run out one day like fossil fuels which are coal, oil, natural gas.

-burning fossil fuels releases carbon dioxide and other gases.

-carbon dioxide contributes to climate change.

-renewable resources such as solar energy or wind energy do not run out.

-most renewable resources don’t emit polluting gases

-solar cells convert to solar energy, solar energy is not always available.

-hydroelectricity is generated by falling water in places where water can be trapped, it is available all the time as long as the reservoir doesn’t dry up.

-wind turbines can be used to generate electricity as long as the wind speed is not too slow or too fast.

-tidal power can generate electricity when turbines in a dam across a river turns as the tides flow in and out, it’s not available all the time but is available at predicted times. sometimes it affects wildlife, but they can place underwater turbines.

-biofuels can be used just like fossil fuels, they are made from animal waste or from plants that are not used for food.

-biofuels are carbon neutral which means they release the same amount of carbon dioxide that was used for the plants to grow.