11782207
Description
Flashcards by finn squires, updated more than 1 year ago
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Created by finn squires
over 6 years ago
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| Question | Answer |
| What are the eight types of energy? | Thermal kinetic gravitational potential elastic potential chemical magnetic electrostatic nuclear Energy is transferred mechanically (doing work), electrically (work done by moving charges), by heating or by radiation (light/sound). |
| What is an open system? | A system in which energy can be transferred in or out of it to the surroundings e.g. central heating, (electricity in thermal out). |
| What is a closed system? | A system in which energy cannot be transferred in or out of it to the surroundings e.g. a bungee jump, (GPE to kinetic to elastic act but not the surroundings). |
| Describe how works done (energy transferred)? | When a force causes an object to move, energy is transferred and work is done. Also when a current flows (work done against resistance in a circuit). |
| Describe the energy changes when throwing a ball upwards? | Chemical ---> kinetic |
| Describe the energy changes when a car brakes? | Kinetic ---> thermal |
| Describe the energy changes in a collision with a stationary object? | Kinetic ---> elastic + thermal + sound |
| Describe the energy transfer in a falling object? | As it falls, with no air resistance GPE ---> kinetic |
| What is specific heat capacity? | Specific heat capacity is the amount of energy needed to raise the temperature of 1kg of a substance by 1oC. |
| What is the conservation of energy principle? | Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed. |
| What is power? | Power is the rate of energy transfer/doing work. 1 watt = 1 J/s. A powerful machine transfers a lot of energy in a short time. |
| What is conduction? | Conduction is the process where vibrating particles transfer energy to neighbouring particles. |
| What is thermal conductivity? | Thermal conductivity is a measure of how quickly energy is transferred through a material by conduction. |
| What is convection? | Convection is where energetic particles move away from hotter to cooler regions. |
| What are the main ways to reduce unwanted energy transfers? | Insulation - reduces heat transfer. Thick walls made from a material with low thermal conductivity. Use thermal insulation e.g. double glazed reduces convection escape. Lubrication - reduce frictional forces. When an object moves there is frictional forces acting on it, this causes some energy to be wasted e.g. air resistance of a falling object kinetic ---> thermal. Objects rubbed together with a lubricant reduces friction by coating them and allowing them to flow easily. |
| What is the formula for efficiency? | Useful energy transfer/total energy transfer. or Useful power output/total power input. |
| What are non renewable energy resources? | Non-renewable energy sources will run out one day. Coal, oil and gas. |
| What are renewable energy resources? | Renewable energy resources will never run out, its renewed as it is used. Sun (solar), wind, waves, hydro electricity, biofuel, tides, geothermal. |
| What is wind power? | Blades turn generator to produce electricity. No pollution, spoils views as many are needed for a substantial production, can be noisy, unreliable as wind is not always blowing, initially expensive, no permanent damage. |
| What are solar cells? | Light energy ---> Electrical energy. Best for small amounts e.g. calculators. No pollution, very reliable in some countries but only in daytime, can't cope for extra demand, initially expensive. |
| What is geothermal power? | Cold water is pumped down and heated by hot rocks. Steam pumped back to turn turbine and power generator, producing electricity. Only in certain areas, reliable, expensive to build compared to energy production. |
| What is hydro electricity? | Kinetic ---> electrical energy from falling water. No pollution, flooding valley to make dam has impacts on environment, can have an immediate response to extra demand, reliable unless drought, initially expensive, small scale in some areas. |
| What is wave power? | Lots of small wave powered turbines to power generator, creating electricity. No pollution, disturbs marine habitats, unreliable as waves aren't always strong (low wind), initially expensive, small scale good on small islands. |
| What are tidal barrages? | Big dams with turbines in as tide comes in water is held back by dam and released in a controlled way turning the turbines, powering the generators and producing electricity. No pollution, prevents boats, disturbs habitats, spoils views. Pretty reliable as tides happen twice a day however low tide produce less energy. Initially expensive, only if suitable estuaries. |
| What are biofuels? | Bio-fuels are renewable energy resources made from either plant products or animal dung. Can be burnt to produce electricity or run cars in the same way as fossil fuels. |
| What are the pros/cons of biofuels? | Pros: Supposedly carbon neutral, although there is some debate about this as only true if you are growing plants at the same rate you are burning them. Fairy reliable as crops take a relatively short time to grow and different crops can be grown all year round. Cannot cope with added demand so crops are grown and stored. cons: very high cost to refine biofuels. Growing crops for biofuels may result in not enough space/water for food crops. Some areas of forest have been cleared to grow the crops so a loss of habitats and decay/burning of vegetation results in CO2 and methane emissions. |
| How do you find the specific heat capacity of a material? | 1. place beaker on a balance and press zero and add the oil to the beaker recording the mass of the oil. 2. place a thermometer and an immersion heater into the oil, read the starting temp of the oil. 3. wrap the beaker in insulating foam to reduce thermal energy transfer to the surroundings. 4. connect a joulemeter and a power pack to the heater and leave the set up for 30 mins. 5. read the number of joules of energy that passed into the heater and the final temp of the oil. 6. use equation to find c. |
| What are the problems with this experiment? | 1. thermal energy passing out of the beaker ( use an insulator with lower thermal conductivity). 2. not all thermal energy passing into the oil (ensure that the heater is fully submerged). 3. incorrectly reading thermometer (use an electric temp probe). 4. thermal energy not being spread through the oil (stir the oil). |
| How do you investigate the effectiveness of thermal insulators? | Different materials; 1. place a small beaker inside a larger beaker. 2. use a kettle to boil some water. 3. transfer 80cm^3 of the hot water into the small beaker. 4. use a piece of cardboard as a lid for the large beaker, with a hole in for a thermometer and make sure bulb is in hot water. 5. record the starting temp of the water and start a stopwatch. then record the temp of the water every three mins for fifteen mins. 6. repeat the experiment using the same volume of hot water but using an insulating material (bubble wrap) to fill the gap between beakers. 7 test a range of different insulating materials e.g cotton wool and polystyrene balls but use the same mass of material. record results in a table and plot cooling curves (most effective=water cools down slower). Thickness; 1. start with a beaker containing 80cm^3 of hot water, and measure the temp of water every three mins for 15 mins. 2. repeat the experiment but wrap two layers of newspaper around the beaker, then 4 etc. plot cooling curve again. |
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