Rotate the position on an ideal circular path and compare the tangential velocity arrow with the inward acceleration vector.
Safety and scientific scope
For uniform circular motion, inward acceleration magnitude a_c=v²/r and net radial force requirement F_c=mv²/r. The arrows point tangent and inward, respectively. 'Centripetal force' is a description of the net inward force supplied by real agents; do not add it as an extra arrow on a free-body diagram already accounting for the actual inward forces.
Vector lengths are indicative; velocity and acceleration have different units. Changing the phase shows the directions rotating at fixed speed, and does not change their magnitude.
Calculated model components (not measured)
Quantity
X component
Y component
Unit
3. Plot the square-speed relation
At fixed mass and radius, inward-force requirement is proportional to speed squared (including when the force-source capacity is inadequate).
Calculated inward force as speed changes (mass and radius held fixed)
Seven different calculation problems drawn at random from eleven. Calculate F=m v²/r in newtons. This is an educational arithmetic model, not a real trajectory planner.