Physics GCSE: Energy
Stored potential energy
Types: Gravitational potential energy, Chemical potential energy, Nuclear potential energy, elastic potential energy
Objects on Earth will have GPE if the attraction between the mass and the mass of the earth.
An object which is further away from the centre of mass of the Earth, then this will increase the GPE of the object.
Elastic potential energy is stored in an object which has been stretched, twist, or deformed from the natural object.
EPE can be stored via the electromagnetic bonds that are formed between the structure.
Efficiency
Energy can never be 100% efficient as there will always be some energy that is lost or transferred to the nearby surroundings.
There can be devices which will be extremely close to being 100% efficient but will never reach 100%.
The second law of thermodynamics states that hot objects will always stay in that state unless something is done to stop that.
Equation of Efficiency of a device: useful energy output of a device/overall energy output of a device
E.g: If a device had an overall output of 200J and it's useful energy output was 80J, you would do 80J/200J then times it by 100 in order to receive a percentage.
Energy and heating
Types of energy transfers: Conduction is the process of energy transferring from one material to another. Conduction will be performed at a higher efficiency within metals as they are good conductors whereas non-metals and gases are poor at this, so they are known as insulators.
Convection occurs when particles with a lot of heat energy in liquids and gases will move and take the place of those particles with little heat energy.
Radiation occurs via electromagnetic waves. Since it requires no particles, it can travel through a vacuum, which is why we still feel the heat that comes from the sun.
Required practical method: Wrap a sheet of newspaper around an 100ml beaker.
Fill the beaker with hot water from a boiled kettle.
Place a piece of cardboard over the top of the beaker like a lid, it needs a hole to be suitable for a thermometer.
Record temp. of water at start and then begin the stopwatch.
Every 120 seconds, record the temp, of the water for 20 mins.
SHC is the amount of energy that can be inputted into a 1 kilogram object to be able to raise the temp. by 1 degree.
The equation for this is: energy = Change in temp x mass x SHC
Energy resources
There are several different types of energy resources. These include Geothermal, Hydroelectricity, fossil fuels, nuclear fuel, biofuels, tidal energy, wave energy, wind energy and the Sun. Burning fossil fuels causes releasing emissions into the atmosphere which include gases such as Carbon Dioxide, Methane and Water Vapour, which are all Greenhouse gases.
Advantages and Disadvantages for renewable: Doesn't release emissions, can be replaced very easily, will not run out within a human's lifespan, there is multiple forms.
It can be expensive, not commercially available, difficult to meet with the demands.
Advantages and disadvantages of non renewables: They can be generated at almost any location with relative ease, they can produce more power, global economy is dependant on it. Environmentally damaging, mightn't be available forever, foundation of political conflict.