Changing tumble overhead at fixed run displacement shows drift as displacement over total time. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
One second tumbles leave one metre per second drift
The run ledger still gives 24 m over 8 cycles. With run time 2 s and tumble time 1 s, total time is 24 s.
24/24=1
Two second tumbles lower drift to three fourths
Tumble time rises to 2 s. Total time becomes 32 s, so drift is 3/4 m/s.
24/32=43
Four second tumbles lower drift to one half
With tumble time 4 s, total time reaches 48 s and drift drops to 1/2 m/s.