Area and speed pairs close to the same steady flow. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Halving area doubles speed
Upstream 2 square metres times 2 metres per second gives flow 4. Downstream 1 times 4 gives the same flow.
2×2=41×4=4
Three by three closes to nine
Upstream 3 square metres times 3 metres per second gives flow 9. Downstream 1 times 9 gives the same flow.
3×3=91×9=9
A wider outlet halves the speed
Upstream 4 square metres times 1 metres per second gives flow 4. Downstream 2 times 2 gives the same flow.