Resistance wire is wound around an aluminium block and connected to a rechargeable power pack. When the circuit is switched on, the wire becomes hotter than the block.
During one interval, the chemical energy store of the power pack decreases by 4.8 kJ. The thermal energy store of the block increases by 3.9 kJ and the thermal energy store of the wire increases by 260 J. The thermal energy store of the surrounding air also increases. No other energy stores change.
The power pack, wire, block and surrounding air are treated as a closed system.
Describe the pathways by which energy is transferred from the power pack to the aluminium block.
Calculate the increase in the thermal energy store of the surrounding air.