Energy Flashcards
What is a system?
A single object or a group of objects that you’re interested in.
What is a closed system?
Systems where neither matter nor energy can enter or leave.
What are ways that energy can be transferred?
Energy is transferred mechanically (by a force doing work), electrically (work done by moving charges), by heating or by radiation (e.g. light or sound).
What is work done?
Energy transferred (usually by a force moving an object)
What is specific heat capacity?
The amoutnof energy needed to raise the temperature of 1kg of a substance by 1°C.
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?
The amount of energy transferred per second.
What is conduction?
Conduction is the process where vibrating particles transfer energy to neighbouring particles.
What is convection?
Convection is where energetic particles move away from hotter to cooler regions. Convection only occurs in liquids and gases.
How does a radiator create convection currents?
Energy is transferred from the radiator to the nearby air particles by conduction.
The air by the radiator becomes warmer and less dense (as the particles move quicker).
The warm air rises and is replaced by cooler air. The cooler air is the heated by the radiator.
At the same time, the previously heated air transfers energy to the surroundings. It cools, becomes denser and sinks.
This cycle repeats, causing a flow of air to circulate around the room - this is a convection current.
How can you reduce frictional forces?
A frictional force acting against a moving object causes some energy to be dissipated. For object that are beign rubbed together, lubricants can be used to reduce the frictional force between the objects’ surfaces when they move. Lubricants are usually liquids, so they can flow easily between objects and coat them.
What are examples of thermal insulation?
Cavity wall insulation, loft insulation, double-glazed windows and draught excluders.
What is efficiency in terms of energy?
The portion of energy transferred to a useful energy store. The less energy that is wasted in the intended energy store, the more efficient the device is said to be.
What are examples of non-renewable energy resources?
Coal, oil and natural gas.
What are examples of renewable energy resources?
Solar, wind, water waves, hydro-electricity, bio-fuel, tides and geothermal.
