p1-energy Flashcards
what is specific heat capacity
the amount of energy required to raise the temperature of 1kg of substance by 1 degrees
formula for shc
change in thermal energy = mass x shc x change in temp
triangle footprint
kinetic energy formula
Ek = 1/2mv(squared)
= 1/2 mass x speed
gravitational potential energy formula
Ep = mgh
= mass x gravity field strength x height
elastic potential formula
Ee = 1/2ke(squared)
= 1/2 spring constant extension
conservation of energy and power principle
energy can be transferred usefully, stored or dissipated but never created or destroyed
what is power
rate of energy transfer
rate of doing work
what is power measured in
watts
power equation
p = energy transferred or work done / time
what is a powerful machine
one that can transfer a lot of energy in a short space of time
where does conduction occur
mainly solids
what is conduction
vibrating particles transfer energy to neighbouring particles
where does convection occur
mainly liquids and gases
what is convection
energetic particles move from hotter to colder region s, transferred by heating the thermal store of the liquids or gases
what happens during convection
warmer, less dense particles rise leaving the cooler denser particles below
how to reduce unwanted energy transfers
lubrication
insulation
double glazing
thick walls
what does lubrications do
reduces friction between objects surfaces
how to improve efficiency
insulation
streamlining
lubrication
formula for efficiency
useful output transfer/power output
———————————
total input transfer/power output
where does most wasted energy go
thermal store
true or false
some devices are 100% efficient
FALSE
non renewable energy
coal
oil
gas
renewable energy
solar wind water waves hydroelectric tides biofuel geothermal
benefit of non renewable
reliable
