Energy Flashcards
What is energy measured in?
Energy is measured in joules.
There is energy in the chemical stores associated with food and fuel.
What is the law of conservation of energy?
Energy cannot be created or destroyed only transferred.
Chemical energy
Food, fuel, batteries
Thermal
Hot objects
Kinetic energy
Moving objects
Gravitational potential
Position in a gravitational field
Elastic
Changing shape, stretching or squashing.
How can energy be transferred?
Electric current, light and sound are ways of transferring energy.
What is dissipation?
Dissipation is a term that it is often used to describe ways in which energy is wasted.
Temperature
An example how energy and temperature are different
You can have a swimming pool and beaker of water at exactly the same temp. The swimming pool represents a much bigger thermal store of energy than the beaker.
The energy needed to increase the temp of a material depends on?
The mass of the material
What the material is made of
The temperature rise you want.
What happens with energy between hot and cold objects?
Energy is transferred from the hot object to the colder one.
Energy will be transferred and the temperature difference will decrease, until the objects are in equilibrium.
How is energy transferred in solids?
It is transferred by conduction.
In conduction, particles transfer energy by colliding with other particles when they vibrate.
Energy transfer happens until the two surfaces are at the same temp.
What is an insulator?
An insulator is a poor conductor.
Wood and many non- metals transfer energy v slowly through them.
Convection
Energy is transferred by convection in liquids and gases.
Heat energy is transferred from hot places to cooler places
Radiation
Energy is transferred by radiation which does not need a medium to travel through.
All objects emit radiation.Travels as waves.
Infrared radiation can be detected by….
Your skin and a thermal imaging camera. It absorbs infared and produces an image.
What are fossil fuels?
Coal, oil and gas are energy resources and are non-renewable.
They can be used to drive a generator in a thermal power station.
They produce a lot of carbon dioxide which is a greenhouse gas.
Also produces pollutants such as sulfur dioxide and nitrogen oxides.
How is electricity generated in a power station?
A fuel burns to heat water and produce steam. The steam drives a turbine, the turbine drives a generator which provides the push that means a current flows in a kettle.
What are renewable resources?
They will not run out.
Wind, tidal, biomass, solar, hydroelectric and geothermal.
Hiw can you calculate power?
Power (W) = energy (j) / time (s)
How can you calculate work?
Work done (J) = force (n) x distance (m)
