The toy drive ledger accepts growth only at matching frequency. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Matching frequency opens the coherent ledger
The drive frequency and natural frequency are both 4 hertz, so the match label is yes.
fdrive=fnat=4Hz
Four accepted kicks add to eight joules
Four kicks of 2 joules each give accepted growth 8 joules.