Energy Flashcards
Explain how energy is conserved
Energy can neither be created nor destroyed- only converted from one form of energy to another
Examples of energy being moved between different stores
An electric kettle is used to heat water
What happens to wasted energy in energy transfers?
The wasted energy is dissipated into the surroundings
Explain ways of reducing unwanted energy transfers in mechanical processes
Reducing friction (lubrication from oil or other liquids)
Explain some ways in which energy is transferred wastefully by mechanical processes
When a machine gets hot
Define efficiency
Efficiency is a way of describing how good a machine is at transferring energy into useful forms
How can efficiency be increased?
Lubrication, thermal insulation, streamlining
What is the formula for calculating energy efficiency?
Efficiency= (useful energy transferred by the device)/(total energy supplied to the device)
Describe ways in which energy can be transferred by heating?
Conduction, convection, radiation, thermal conductivity
Describe ways of reducing unwanted energy transfers using thermal insulation
Double glazing, loft insulation, cavity wall insulation, fitted carpets, curtains, draft excluders
Define thermal conductivity
The ability of a material to conduct heat from its one side to the other
Describe the effects of the thickness and thermal conductivity of the walls of a building on its rate of cooling
the thicker the wall the smaller the rate of thermal conductivity
What are the different factors that affect the gravitational potential energy stored in an object?
Gravitational field strength, mass and height
What is the equation for GPE?
Change in GPE= mass x GFS x change in height
What are the different factors that affect the kinetic energy stored in an object?
Mass and speed
