Physics Energy & Power P1

What are the 10 forms of energy?

Magnetic, Kinetic, Thermal, Light, Gravitational, Chemical, Sound, Elastic, Electrical, Nucleur

What is energy?

Energy is the ability to do work

What is a system?

• An object or group of objects working together

• A system is more efficient if it can produce the same output energy with less input energy. That is if it can do the same job using less energy

What are the 8 stores of energy?

Kinetic, Gravitational Potential, Chemical, Elastic potential, Nucleur, Electrostatic, Magnetic, Thermal

There are 4 pathways..

• Mechanical work (when a force moves through a distance)

• Electrical work (when a charge moves through a potential difference)

• by Heating (because of a temperature difference)

• by Radiation (light, microwaves, sound)

What is efficiency?

When energy is changed from one form to another, some energy is changed into forms that are not useful

Why are some light bulbs given higher energy rating than others and how can we make the light bulb more efficient?

• less input energy becomes heat

• less heat makes it more efficient

Why are some washing machines given higher energy rating than others and how can we make the washing machine more efficient?

• Same output but less input energy the less noise the more efficient it will be

• shorter wash cycle wash at lower temporal and reduce the friction of the drum

Sankey diagrams example

A microwave transfers electrical energy into 400J of energy to cook food. It has an efficiency of 80%

How much electrical energy is used in total?

400 / 0.8 = 500J so 500J - 400J = 100J (waste) Meaning 400J useful So the diagram should have 500 written on the side with 400J to the right as useful 100J down as waste and based on how much each box is you make the arrows that big for example the boxes are 50J each then there would be 8 lines for 400 and 2 for 100

Explain why not all the gravitational potential energy store is transferred to kintetic. Where does some of it go?

It goes around resistance/ friction

What is scientific law?

The scientific law of conservation of energy tells us that “energy cannot be created or destroyed, it can only be transferred from one form to another“. Some will be transferred into the useful form we want but some will always be transferred into useless forms and will be wasted (often as heat)

Efficiency calulations

Efficiency(%) = useful energy transferred by the device / total energy supplied to the device (x100%)

Symbols - Power

• Power = Energy / Time

• Power = Watts / Time

• 1 Watt = 1 Joule per second

Symbols - Work done

Work done(J) = force(N) x distance moved in the direction of the force (m)¹

National and Global energy resources

• Some resources are renewable being (or can be) replenished as it is used

• Some resources are non-renewable not replenished as it is used

Fossil fuels (Coal)

• not renewable

• Used for electricity and heating

• ENVIRONMENT IMPACT - contributions to global warming from CO2 emissions and significant air pollution

Fossil fuels, such as coal, are non-renewable energy sources that are primarily used for electricity generation and heating. Their use contributes significantly to global warming due to CO2 emissions and results in considerable air pollution.

Fossil fuels (Oil)

• not renewable

• Used for transport, heating, electricity

• ENVIRONMENT IMPACT - Greenhouse gas emissions from burning and extraction contribute climate change

Fossil fuels (Gas)

• not renewable

• used for transport, electricity, heating

• ENVIRONMENT IMPACT - Greenhouse gas emissions (CO2, Methane) also leading to global warming and climate change

Nuclear

• not renewable

• used for electricity

• ENVIRONMENT IMPACT - Management of radioactive waste, potential for catastrophic accidents and the impacts of uranium mining

Bio-fuel

• renewable

• used for transport, electricity, heating

• ENVIRONMENT IMPACT - Production leads to deforestation, habitat loss and sol degradation from large scale agriculture

Wind

• renewable

• used for electricity

• ENVIRONMENT IMPACT - Noise pollution, visual impact on the landscape and potential disruption of local habitats during construction

Hydro-electricity

• renewable

• used for electricity

• ENVIRONMENT IMPACT - Destruction of ecosystems and fish migration, dam construction while also producing methane from reservoirs and altering river flow

Geothermal

• renewable

• used for electricity, heating

• ENVIRONMENT IMPACT - some greenhouse gases released and also the rise of triggering minor earthquakes

Tidal

• renewable

• used for electricity

• ENVIRONMENT IMPACT - could be habitat loss and disruption of marine life due to the turbines

Sun

• renewable

• used for electricity, heating

• ENVIRONMENT IMPACT - could be habitat loss, land loss, and potentially the disposal of solar panels could be damaging

Waves

• renewable

• used for electricity

• ENVIRONMENT IMPACT - impact marine ecosystems by creating noise, electro-magnetic fields from under water cables and potential habitat damage

Example of discussing advantages and disadvantages

The advantages and disadvantages of wind over coal are wind energy is renewable whereas coal is non renewable. Wind produces virtually no greenhouse gases unlike coal which is highly polluting. Although coal is consistent and in demand wind energy is very affordable effective without much damage.

PREFIXES

• kilo K = 1000 = 1 × 10³

• mega M = 1,000,000 = 1 × 10⁶

• giga G = 1,000,000,000 = 1 × 10⁹

• terra T = 1,000,000,000,000 = 1 × 10¹²

Therefore new formula is -

• Energy (in kWh) = power (in kW) x time used in (hrs)

what happens to wasted energy?

Transferred around the surroundings as heat