Holding drag coefficient fixed while speed changes makes the opposing force readable. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Two metres per second gives two newtons of drag
Hold the drag coefficient at 1 N*s/m. Speed 2 m/s gives drag 2 N.
1⋅2=2
Four metres per second gives four newtons
The coefficient stays 1 N*s/m. Doubling speed to 4 m/s doubles drag to 4 N.
1⋅4=4
Six metres per second gives six newtons
Speed 6 m/s gives drag 6 N. Three rows show linear drag without a fitted curve.