P15: Energy Transfers and Efficiency Flashcards
Conservation of energy
Energy cannot be created or destroyed.
How can energy be stored?
> Elastic Potential Energy is stored when something is stretched.
> Gravitational Potential Energy is stored when an object is lifted.
Useful Energy
Energy transferred to where it is wanted, in the form that it is wanted.
Wasted Energy
The energy that is not usefully transferred.
What usually happens to wasted energy?
It spreads out and dissipates.
What happens as energy spreads out?
It becomes less useful.
Efficiency =
Useful power out/ total power in. (x 100)
Sankey Diagram
Used to measure efficiency
The lower the U-Value of a material…
… The more effective it is as an insulator.
U-Values
A measure of the energy per second that passes through a material when the temperature differnece across it is 1C.
4 features of a well insulaed house.
> Loft Insulation. (Fibreglass is good)
> Cavity wall insulation.
> Tin foil behind the radiators
> Double glazed windows.
