Topic 1

• The equation for kinetic energy is ½ m v² where m is mass, v is velocity, and J is energy (Joules).
• The equation for elastic potential energy is ½ k x² where k is spring constant, x is extension, and J is energy (Joules).
• The equation for gravity potential energy is mgh where m is mass, g is gravitational field strength, and h is height, all in SI units (Joules).
• Specific Heat Capacity is the amount of energy needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius.
• Power is the rate at which energy is transferred or rate at which work is done.
• The unit of power is Watt (W).
• When a ball is thrown upwards and then returns to its starting position, the energy changes involve conversion of kinetic energy to gravitational potential energy, maximum gravitational potential energy, and conversion of gravitational potential energy to kinetic energy.
• A bungee jumper slows down once the cord begins to stretch because kinetic energy decreases as it is converted to elastic potential energy, and since kinetic energy is proportional to velocity, as kinetic energy decreases, so does velocity.
• Examples of chemical energy stores include food, fuel (wood, coal, petrol), and batteries.
• In a typical house, heat energy escapes to the outside environment, which can be reduced by using thermal insulation and lubrication.
• Thermal insulation in buildings is used to reduce heat loss by conduction, which is when heat is lost directly through a solid like a wall or a window.
• Houses tend to have thick walls made from materials with a low thermal conductivity, which means they don't conduct heat very well.
• Houses also tend to have cavity walls, which are two layers of bricks with a small air gap or cavity between them, to reduce conduction because air is a poor conductor.
• The problem with cavity walls is that the air gap allows convection, so insulating foam is filled in the gap to reduce heat loss.
• Single glazing, which is what older houses tend to have, has just one pane of glass, making it easy for heat to be lost by conduction.
• Double glazing, which is more common in new houses, has two layers of glass with a tiny air gap between them, reducing conduction because the heat can't be conducted across the air gap and from inside the house to outside.
• Lubrication is used to reduce friction, which is the resistance that an object encounters when moving over a solid or through a fluid, as it reduces the efficiency of energy transfer and can cause objects to heat up.
• The friction between the cogs and chain of a bicycle makes it harder to pedal, but adding oil, a type of lubricant, can reduce that friction and make cycling easier.
• Streamlining cars and planes reduces the friction from air resistance, allowing them to use less fuel and be more efficient.
• Power is the rate at which energy is transferred, which can be calculated by the equation power equals energy transferred divided by the time it took to transfer that energy.
• Power is also the rate at which work is done, which can be calculated by the equation power equals work done over time.
• The term work done is a special measure of the energy transferred and is used when a force is used to move an object by a certain distance.
• Power is measured in watts, while energy transferred, work done, and time are measured in joules and seconds respectively.
• The rest of the world consumes large amounts of non-renewable energy resources like coal, oil, and natural gas, which are referred to as fossil fuels.
• In the past 50 years, there has also been a significant rise in the use of a new generation of renewable resources including solar, wind, hydroelectric, geothermal, biofuels, tidal, and many more.
• Domestic uses refer to household things like cooking and heating, with natural gas as the main source of heat.
• Coal is another non-renewable source of heat that can be used in fireplaces.
• There are also some rare renewable sources of heating such as solar water heaters and biofuels that can be burned over heat in a similar manner to coal.
• In the UK, almost 60 percent of electricity is from fossil fuels and non-renewables together make up nearly 80 percent, so the vast majority of our electricity is from non-renewable resources.
• Wind power can be captured through the use of wind turbines, which are often placed in exposed areas like malls or coasts where there's lots of strong winds.
• Each turbine has a generator inside it, which turns as the blades spin, converting the kinetic energy from the movement into electrical energy that can then be transported to the national grid.
• Solar power is generated by solar cells, which are often in the form of solar panels, and generate electric currents directly from sunlight, much like plants trap the sun's energy through photosynthesis.
• Solar energy works well in low energy devices like watches and calculators, so that we don't have to replace batteries, and in remote regions like the Australian outback which aren't connected to the main power grid.
• The pros and cons of wind and solar energy are similar, both having very low running costs and not producing any pollutants, particularly carbon dioxide.
• The main issue with wind and solar energy is that they're both dependent on the weather, as they don't generate electricity if the wind doesn't blow or the sun doesn't shine.
• Both wind and solar energy take up a lot of space, especially because you need so many of them to produce a significant amount of power.
• Some people complain that wind turbines are not very aesthetically pleasing and can be noisy.
• Neither wind nor solar energy damage the environment, and both are getting cheaper every year.
• Geothermal power is thermal energy generated and stored in the earth's crust, originating from the initial formation of our planet and the ongoing radioactive decay of materials like uranium deep inside the earth.
• Geothermal energy is the same type of energy that heats hot springs across the world.