A closed motor cycle cites the waste channel as part of the energy ledger. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Waste heat is a required budget source
The audit cites waste heat 24 joules alongside useful work 36 joules.
36+24
Waste keeps the input honest
Useful work plus waste returns the packet input 60 joules.