Energy Flashcards
energy stores
thermal
kinetic
gravitational potential
elastic potential
chemical
magnetic
electrostatic
nuclear
pathways
mechanical
electrical
radiation (light, sound)
heating
work done
another way to say energy transferred
can be done when a current flows (work done against resistance) or by a force moving an object
falling objects also transfer energy
gravitational potential transferred into kinetic
kinetic energy
energy transferred into this store when oject speeds up and transferred out when object slows down
specific heat capacity
the amount of energy needed to raise the temperature of 1kg of a substance by 1℃
how much energy a substance can store
investigating specific heat capacity
- block of mterial with holes for heater and thermometer
- measure mass of block
- wrap it in insulating layer to reduce energy transferred from the block to the surroundings
- insert thermometer and heater
- measure initial temperature of the block
- as the block heats up, use the thermometer to measure its temperature every minute
how does this practical work (energy transfers
when you turn the power on, the current does work on the heater, transferring energy electrically from the power supply to the heater’s thermal energy store. this energy is then transferred to the materials thermal energy store by heating causing the materials temperature to increase
The law of the conservation of energy
Energy can be transferred, stored or dissipared but never created or destroyed
Conduction
mainly in solids
the process where vibrating particles transfer energy to neighbouring particles
the particles in the part of the object being heated vibrate more and collide with eachother. These collisions cause energy to be transferred between particles’ kinetic energy stores
process continues through object until the energy is transferred to the other side
thermal conductivity
measure of how quickly energy is transferred through a material by conduction
high thermal conductivity transfers energy between particles quicker
convection
only in liquids and gases
energetic particles move away from hotter to cooler regions
diffusion down a concentration gradient
particles can move in fluids
particles move faster when heated
space between particles increases
density of region decreases
warmer, less dense region will rise
if heating is constant, convection current can be created.
radiators
create convection currents
energy transferred from radiator to nearby air particles by conduction
air by radiator becomes warmer and less dense
warm air rises, replaced by cool air that is heated by radiator
previously heated air transfers energy to surroundings, becomes cooler and condenses
cycle repeats causing a flow of air called a convection current
house insulation
cavity walls: air gap between inner and outer walls reduces heat loss by conduction. if gap filled with foam, prevents convection as well
loft insulation: fiberglass wool
double glazed windows: works same as cavity walles with air gap between to sheets of glass
draught excluders around doors and windows reduce energy loss by convection
non-renewable energy sources
will run out one day
- fossil fuels ( coal, oil, natural gas)
- nuclear fuel (uranium, plutonium)
typically burnt to release energy
