Energy Flashcards
What are the 8 energy stores and where can we find them?
- Chemical - e.g. food we eat
- kinetic -e.g. movement energy
- Gravitational - e.g. object that are lifted up
- Elastic - e.g. from springs
- Thermal - e.g. from hot objects
- Magnetic - e.g. objects in magnetic fields
- Electrostatic - e.g. charged objects
- Nuclear - e.g. stored within a nucleus
what is the conventions of energy (is energy created?)
In any process, energy is never created or destroyed. (It is just transferred from one store to another.)
what is the formula of the relationship between efficiency, useful energy output and total energy output?
Efficiency = useful energy output/ total energy input (x 100)
how is the role of convection important in our everyday life?
- Convection can be helpful by distributing heat energy.
e. g: a radiator that heats up the whole room. Hot air rises away from it, creating a current of cool air to be heated.
How does conservation of energy produce a link between gravitational potential energy, kinetic energy, and work?
Because energy is conserves the decrease in GPE = increase in KE, for a falling object if no energy is lost to the surroundings
describe power as the rate of transfer energy or rate of doing work:
what is the formula of power?
power is the rate of transfer energy or the rate of work done. so p = E/t
power = work/ time
what is the formula for the relationship between power, work done (energy transferred) and time taken?
power = work done/ time
or
watts = joules/ seconds
or
N = J/S
how does thermal energy transfer takes place by conduction?
- conduction is the main method of thermal energy transfer in solids.
- when a material is heated, atoms start to move around (vibrate more), as they move, they bump into each other, transferring energy from atom to atom.
how does thermal energy transfer may take place by convection?
- convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy.
- heat energy is transferred from hot places to cooler places by convection.
- liquids and gases expand when they are heated.
how does thermal energy transfer may take place by radiation?
thermal radiation is the transfer of energy by infrared (IR) wave
how is emission and absorption of radiation related to light?
light (and shiny surfaces) are good reflectors of IR meaning it is poor at observing it.
how is emission and absorption of radiation related to the dark?
- dark (matt surfaces) are poor reflectors meaning it is good at absorbing IR.
- this means that if you place a heat source next to a dark object, it will heat up faster than if a light one.
how is emission and absorption of radiation related to temperature?
- hot objects produce more IR per second.
- also the higher the temperature, the higher the frequency of EM (electromagnetic) waves emitted.
what does insulation do?
it reduces the heat energy lost since they can’t conduct heat and no convection currents can be formed
what does double glazing do?
Keeps your home more energy efficient and reduces sound.
The argon gas is a poor heat conductor and therefore keeps warm air from escaping, while the second pane of glass acts as a barrier to noise.
