Energy Transfer Flashcards
Where are there energy transfers in a closed system
Energy can be transferred between energy stores within a closed system e.g. kinetic energy to a thermal store in engine/car
How can energy be wasted in a system
Friction between moving parts
Electrical resistance
Unwanted sound energy
How to reduce unwanted energy transfers
Thermal insulation - reduces wasted thermal energy transfer
What affects the rate of cooling of a building
High thermal conductivity will cool down faster than one with wall of low thermal conductivity
Describe energy transfer by conduction
When part of a solid absorbs heat energy the atoms vibrate faster and with bigger amplitude, these vibrations pass from atom to atom transferring heat energy
Equation for thermal energy
Thermal energy = mass x specific heat capacity x change in temperature
Units and symbols for the quantities in thermal energy equation
Thermal energy : Q joule or kilojoule
Mass : m kilogram
Specific heat capacity : c joules/kilogram°c
Change in temperature : ^T
Define specific heat capacity
The energy required to raise one kilogram by one degree
