Flashcards in Building Brick Questions Deck (53):
What is the difference between conductors and insulators?
Conductors are materials that are good at transferring thermal energy, insulators are not.
Which materials are the best conductors? Why?
Metals are the best conductors. This is because delocalized electrons move through the material faster transferring thermal energy.
Which materials are the best insulators?
Non-metals are the best insulators. Especially materials with air pockets in.
What is thermal conductivity?
Thermal conductivity is a measure of how good a material is at transferring thermal energy.
How does thermal conductivity relate to rate of energy transfer?
The higher the thermal conductivity, the faster the rate of energy transfer.
How does thickness of an insulator effect rate of energy transfer?
The thicker an insulator, the lower the rate of energy transfer.
Which objects emit and absorb infrared radiation?
All objects will emit (give out) and absorb (take in) infrared radiation.
Objects of which colour are best at absorbing and emitting radiation?
Dark, matte objects are the best absorbers and emitters of radiation.
Objects of which colour are best at reflecting radiation?
Shiny, light coloured objects are the best reflectors of radiation.
How does temperature relate to the amount of infrared radiation emitted?
The higher the temperature, the more infrared radiation is emitted (given out).
What is blackbody radiation?
Blackbody radiation is radiation emitted by a body that absorbs all the radiation incident on it (all radiation that hits it).
How does infrared radiation increase the temperature of objects?
If an object absorbs more infrared radiation than it emits, it's temperature will increase.
How does the mass of an object affect the amount of energy needed to heat is?
The larger the mass of an object, the more energy is needed to increase its temperature.
Give five different methods of heating a home.
Electric heaters, gas heaters, gas-fired central heating, oil fired central heating and solid-fuel stoves.
Give five different methods of insulating a home.
Loft insulation, cavity wall insulation, double-glazed windows, aluminium foil behind radiators and external walls made from thicker bricks with a lower thermal conductivity.
What is cavity wall insulation?
Cavity wall insulation is insulation material that is used to fill the cavity between the two layers of bricks of an external wall of a house
What is the specific heat capacity of a material?
The specific heat capacity of an object is the amount of energy needed to heat 1kg of a material by 1°C.
What is a system?
A system is an object or group of objects?
What are the six energy stores?
Energy can be stored as: Chemical, Gravitational Potential, Kinetic, Elastic Potential, Thermal, and Internal.
What are 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 is a system where no energy can be transferred into 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 objet 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.
How will the total energy input into 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 percent efficient?
No machine is 100 percent efficient. Some energy is wasted as heat due to friction between moving, 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 most of the electrical energy used in the home?
Gas and oil provide most of the electrical energy used in average home.
What is power? (in Physics)
Power is how fast energy is transferred.
How are most appliances connected to mains?
Most appliances are connected using a three core cable.
What colour code for the insulation wires is used in the UK?
Live - Brown
Neutral - Blue
Earth - Green and Yellow
What is the purpose of the live wire?
Live wires carries alternating current to the appliance
What is the purpose of the neutral wire?
Neutral wire carries the alternating current back to mains.
What is the purpose of the earth wire?
The Earth wire is a safety wire to stop the appliance becoming "live".
What are the potential differences across each wire?
Live - approx. 230V
Neutral - approx. 0V
Earth - approx. 0V
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 replaces after it is used
What is a non-renewable energy source?
A non-renewable resource is one that cannot be replaces 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 by using fossil fuels.
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 of 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 living organisms take 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 produce nuclear waste.
Give one disadvantage of renewable energy resources.
Renewable energy resources cover large areas, aren't always reliable and can disturb natural habitats.