Topic 1 Energy Flashcards
What are the energy store you need to know?
Thermal, kinetic, gravitational potential, elastic potential, chemical, magnetic
In which ways can energy be transferred?
Mechanically, electrically, by heating, radiation
What happens to energy when a system changes?
Energy is transferred. It can be be transferred into or away from the system, between different objects in the system or between different types of energy stores.
What are closed systems?
Where neither matter nor energy can enter or leave. The net change in the total energy of a closed system is always zero.
What is work done?
Another way of saying energy transferred.
When can work be done?
When current flows or by a force moving an object.
How do falling objects transfer energy (give an example)?
When something is dropped from a height, it’s accelerated by gravity. As it falls, the gravitational potential energy store is transferred to its elastic potential energy store.
When there is no air resistance present, what is energy lost in the g.p.e store equal to?
The energy gained in the kinetic energy store.
What has a kinetic energy store?
Anything that is moving.
When is kinetic energy transferred in and out of an object’s store?
Energy is transferred to the store when an object speeds up and is transferred when it slows down.
Why is energy ever transferred to the g.p.e store of an object?
Lifting an object in a gravitational field requires work, this causes a transfer of energy to the g.p.e store of the raised object.
The higher the object I’d lifted, the more energy is transferred to this store.
When can elastic potential energy be transferred to the store of an object?
Stretching or squashing an object can transfer energy to its elastic potential energy store.
When can you not use an equation to find out the elastic potential energy of a stretched spring?
If the limit of proportionality has been exceeded.
What is specific heat capacity?
The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree.
What is the conservation of energy?
Energy can be transferred usefully, stored or dissipated but can never be created or destroyed.
What happens to the energy in a store when it is transferred?
Some of it is transferred usefully but some is dissipated when an energy transfer takes place.
What is power?
The rate of energy transfer, or the rate of doing work.
What is one watt equivalent to?
One joule of energy transferred per second.
What is conduction?
The process where vibrating particles transfer energy to neighbouring particles.
Where does conduction occur?
Mainly in solids
In conduction what happens to the energy transferred to an object by heating?
The energy is transferred to to the thermal store of the object. This energy is shared across the kinetic stores of the object.
In conduction, what happens to the particles in the part of the object being heated?
They vibrate more and collide with each other. These collisions cause energy to be transferred between particles’ kinetic energy stores.
In conduction, what happens when the process continues throughout the object?
The process continues throughout the object until energy is transferred to the other side of the object. It’s then usually transferred to the thermal stores of the surroundings (or anything else touching the object.)
What si convection?
Where energetic particles move away from hotter to cooler regions.
Where does convection occur?
Only in liquids and gases because the particles are free to move around.
In convection how is energy transferred to the thermal store of the liquid or gas?
By heating.
What happens when you heat the regions of a liquid or gas?
The particles move faster and the space between individual particles increases. This causes the density of the region being heated to decrease.
In convection, what happens when one region (of a gas or liquid) is heated in comparison to the other region?
Because liquids and gases can flow, the less dense and warmer region will rise above the denser and cooler region. If there is a constant heat source, a convection current can be created.
How can you reduce unwanted energy transfers?
Lubrication can reduce friction between surfaces, meaning that the energy caused by the frictional force is not dissipated.
How can you prevent energy losses in the house?
Have thick walls- use thermal wall insulation, double glazed windows, draught excluders.
What sort of material should thick walls be made from?
A material with a low thermal conductivity because the thicker the walls and the lower their thermal conductivity, the slower the rate of energy transfer will be.
What can you do for thermal insulation in the house?
Cavity wall insulation, lost insulation, double glazed windows, draught excluders.
