Physics 1

• A system is an object or group of objects.
• When a system changes, the way energy is stored also changes.
• Kinetic Energy 𝐸𝐸 𝑘𝑘 = 1 2 𝑚𝑚𝑣𝑣 2 Where m is the mass in kilograms, kg, v is the speed, in metres per second, m/s and the kinetic energy, E k , in joules, J.
• Main Energy Uses include Transport, Electricity generation, and Heating.
• Extraction of Energy from Fossil fuels involves destroying landscapes.
• Wind turbines can be considered an eyesore.
• Use of Energy Sources from Fossil fuels releases harmful emissions.
• Solar and wind energy sources directly create electricity with no emissions.
• During the industrial revolution, fossil fuels became an important source of energy as it was easy to mine, and provided a lot of energy.
• Only recently has renewable energy become more suitable – technology has had to develop a lot since industrial revolution to be able to harness such energy sources efficiently.
• It is easier to use energy resources due to increasing pressure to cope with the public’s increasing power demands but harder to solve environmental issues due to political, social, ethical and economic considerations.
• Elastic Potential 𝐸𝐸 𝑒𝑒 = 1 2 𝑘𝑘𝑒𝑒 2 Where E e , is the elastic potential energy, in joules, J, k is the spring constant, in newtons per metre, N/m and e is extension in metres, m.
• Gravitational Potential Energy 𝐸𝐸 𝑝𝑝 = 𝑚𝑚𝑚𝑚ℎ Where E p , is the gravitational potential energy, in Joules, J g is the gravitational field strength ( 9.8 ��𝑚𝑠𝑠 −2 ), in newtons per kilogram, N/kg, and ‘h’ is the height in metres, m.
• Power = Energy / Time
• Specific Heat Capacity 𝐸𝐸 = 𝑚𝑚𝑚𝑚∆𝑇𝑇 Where the change in thermal energy, ∆E, in joules, J , mass, m, in kilograms, kg, the specific heat capacity c, in joules per kilogram per degree Celsius, Jkg −1 °C −1 and the temperature change, ∆ T in degrees Celsius, °C
• Lubrication in a motor reduces friction, so less energy is lost as heat through friction.
• Thermal insulation, such as double glazing, reduces the amount of useful thermal energy lost.
• The higher the thermal conductivity of a material, the more easily heat is allowed to travel through the material, leading to a higher rate of energy transfer by conduction across the material.
• If the walls of a building are thick and have low thermal conductivity, the rate of cooling is low.
• If the walls of a building are thin metal sheets, heat would be lost very quickly.
• The efficiency is the ratio of the useful work done by a machine, engine, device, etc, to the energy supplied to it, often expressed as a percentage.
• The efficiency of a system can be increased by reducing waste output (lubrication, thermal insulation, etc.) and recycling waste output (absorbing thermal waste and recycling as input energy).
• Non-renewable energy sources include fossil fuels (coal, oil, gas), nuclear fuel, and renewable energy sources include biofuel, wind, hydro-electricity, geothermal, tidal, solar, and water waves.
• Renewable energy is energy which can be replenished as it is used, for example, wind will never stop.
• Non-renewable energy is used more for large-scale energy supplies due to the large energy output per kilogram of fuel, renewable resources cannot provide such a large amount of energy as easily.
• Renewable energy has become more important due to the finite lifetime of fossil fuels, and so their development has become more important.
• Renewable energy is not always the most reliable as solar doesn’t work in bad weather or night and wind is only intermittent.
• Power Power is defined as the rate at which energy is transferred or the rate at which work is done.
• Power = energy tranferred time = work done time = 𝑃𝑃 = 𝐸𝐸 𝑡𝑡 = 𝑊𝑊 𝑡𝑡
• An energy transfer of 1 joule per second is equal to a power of 1 watt.
• If given two motors A and B, the motor that can do the same work faster is more powerful – as the energy is transferred at a faster rate
• Energy Transfers Energy can be transferred usefully, stored or dissipated but cannot be created or destroyed.
• In all system changes energy is dissipated, so that it is stored in less useful ways
• This energy is often described as being ‘wasted’.