How this calculator works
This page reports the inward net radial force in an inertial frame. Both descriptions use the same magnitude for steady circular motion. Enter the radius of the actual path, measured from the rotation axis. The equivalent Earth weight mass divides force by standard gravity and is a comparison only; the object's inertial mass stays unchanged. The model does not include tangential acceleration.
Formula
F = m v²/r = m omega² r; a_r = F/m; equivalent Earth weight mass = F/9.80665.
Worked example
A 2 kg mass moving at 3 m/s on a 3 m radius circle requires a radial force of 6 N. At 2 rad/s, a 4 kg mass on a 3 m radius has radial force 48 N.
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Frequently asked questions
Which way does the force point?
It is towards the centre. This is the net radial force, which may be supplied by tension, friction or gravity.
Why does doubling speed matter so much?
Force depends on speed squared, so doubling speed at unchanged radius and mass quadruples force.
Can I solve mass at zero speed?
No. Zero speed gives zero radial acceleration and does not determine mass from radial force.