energy Flashcards
Name 4 energy stores
thermal kinetic gravitational potential elastic potential chemical magnetic electrostatic nuclear
what is a system
a single object or group of objects that you are interested in
when a system changed
energy is transferred
what is work done
energy transferred
describe the energy transfer when wind hits a windmill
the energy transfers from the gravitational potential energy store of the wind to the kinetic energy store of the windmill
what is the equation for kinetic energy
ek=1/2mv^2
what is the equation for gravitational potential energy
ep=mgh
when something falls
energy from its gravitational energy store is transferred to its kinetic energy store
what is the equation for elastic potential energy
ew=1/2ke^2
more energy needs to be transferred to the … energy store of some materials to … their temperature
thermal energy store, increase
what is the equation for specific heat capacity
/\E=mc/\ø (mass x specific heat capacity x temperature change
energy can never be … nor …
created , destroyed
dissipated energy can also be called
wasted energy
lubrication reduces
frictional forces
heating can occur by two methods, these are:
convection and conduction
an equation linking power,energy transferred and time is:
p=e/t
an equation linking: power, work done and time is:
p=w/t
insulation reduces the rate of what transfer and how?
energy transfer
and
heating
useful devices are useful because
they can transfer energy from one store to another
the equation linking useful energy transfer, efficiency and total input energy transfer is
efficiency= useful output energy/total input energy
electric heaters are usually …% effective
100
name some non renewable recourses
coal
oil
natural gas
name renewable energy stores
the sun wind waves hydroelectricity bio-fuel tides geothermal
non renewable recourses are…
reliable
one disadvantage of non renewable recourses
releases harmful gases weakening the o zone
