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Energy
Energy flash cards
Question | Answer |
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What is a system? | A system is an object or group of objects. |
What is a system? | Energy can be stored as: Chemical, Gravitational Potential, Kinetic, Elastic Potential, Thermal, Internal. |
What are the four methods of transferring energy between stores? | Energy is transferred by heating, by waves, by electric current, or by a force moving an object. |
What is the law of conservation of energy? | Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed. |
What is a closed system? | A closed system is a system where no energy can be transferred in to or out of the system. |
How does the energy in a closed system change during an energy transfer? | The total energy of a closed system is the same before and after the transfer of energy. |
What is work done (in Physics)? | Work done on an object is the amount of energy transferred to the object by a force acting over a distance. |
How does friction effect work done? | Work done to overcome friction is transferred energy to the thermal energy stores of the objects that rub together. |
What is the gravitational potential energy store? | The gravitational potential energy store of an object increases when it is lifted up because work is done to overcome gravitational force. |
What determines how big the gravitational field strength is? | The gravitational field strength of a star or planet is linked to its mass. Earth is more massive than the moon. |
What is the kinetic energy store? | The energy in the kinetic energy store of a moving object depends on its mass and speed. |
What is the elastic potential energy store? | Elastic potential energy is the energy stored in an object when it is stretched. It is proportional to the square of the extension (assuming |
How will the total energy input in to a system be used? | Of the total energy input into a system, a fraction will be useful and the rest will be wasted. |
What happens to energy that is wasted in a system? | Wasted energy dissipates to the surroundings which become warmer. |
Why is no machine 100% efficient? | No machine is 100% efficient. Some energy is wasted as heat due to friction between moving parts, air resistance, electrical resistance and noise. |
How could we improve efficiency? | Efficiency can be improved by using lubrication on moving parts, make the machine more aerodynamic, reducing electrical resistance and noise. |
What provides mots of the electrical energy used in home? | Gas and oil provide most of the electrical energy used in average homes. |
What is power (in Physics)? | Power is how fast energy is transferred. |
What are the main energy resources? | The main energy resources are; Fossil Fuels, Nuclear Fuel, Biofuel, Wind, Hydroelectricity, Geothermal, Tidal, Solar and Waves. |
What is a renewable energy source? | A renewable energy source is one that can be replenished or replaced after it is used. |
What is a non-renewable energy source? | A non-renewable resource is one that cannot be replaced after it is used. |
What can energy resources be used for? | Energy resources can be used for transport, generating electricity and heating |
How is most of the global energy demand met? | Most of the energy demand across the world is supplied using fossil fuels (coal, oil and natural gas) |
Give two examples of fuels in nuclear power stations | Uranium and plutonium is used as the fuel in a nuclear power station. |
Give one benefit or nuclear fuels as an energy source over fossil fuels | Much more energy is released from 1kg of uranium or plutonium as compared to fossil fuels |
Biofuels are considered to be carbon neutral. What does carbon neutral mean? | Carbon neutral, in theory, implies that the carbon a living organism takes in during its lifetime balances the amount released when it is burnt. |
Give one disadvantage of fossil fuels | Fossil fuels produce increased levels of greenhouse gases, which could cause global warming |
Give one disadvantage of radioactive waste | Nuclear fuels product radioactive waste |
Give one disadvantage of renewable energy resources | Renewable energy resources cover large areas, aren’t always reliable and can disturb natural habitats. |
Give one advantage of gas-fired and pump-storage power stations | Gas-fired and pump-storage power stations can meet the variations in demand |