energy stores and transfers Flashcards
(10 cards)
1
Q
what is the formula for efficiency
A
efficiency = useful energy output / total energy output
2
Q
why does the hard drive work at a lower temperature when the black one is on top
A
- heat is transferred by conduction
- thermal energy is emitted
- in the form of radiation
- more thermal energy is emitted when a larger black surface is exposed
- which means the heat will transfer between the two surfaces until they reach the same temperature
3
Q
describe transfer of heat to potato in water in pan
A
- as hot plate heats up, energy is transferred to the plate through conduction
- heat energy is conducted through the pan
- heat energy is transferred from the pan to the water by conduction
- energy is distributed through the water by convection
4
Q
describe the energy transfers from water reservoir to turbine
A
- water initially has energy in gravitational store
- as water falls, energy is transferred to the kinetic store of water
- as water turns the turbine, energy is transferred to the kinetic store of the turbine
- energy is transferred electrically through cables
5
Q
renewable sources of energy
A
- solar energy
- wind
- bio fuel
- hydroelectricity
- geothermal
- tidal
6
Q
non renewable energy resources
A
- fossil fuels
- nuclear fuel
7
Q
how can you generate electricity from energy sources
A
- turbine is turned
- ## which turns a generator which generates electricity
8
Q
how can you generate electricity from fossil fuels
A
they can be combusted to heat water, and the steam produced can be used to turn turbines
9
Q
advantages of nuclear resources
A
- reliable
- produces large amounts of energy consistently
- no pollution or co2
10
Q
disadvantages of nuclear resources
A
produces radioactive waste that takes thousands of years to decay
expensive to build and maintain
cannot respond to changes in demand
