You've gotten out of Earth's gravity well - good for you! However, you're feeling a bit uncomfortable in zero-gravity, and you want to replicate 1 \$g\$ of force in a centrifuge. Use the equation for force in a centrifuge: $$\text{RCF} = \frac{r_\text{m} \, \left(\frac{2 \pi N_\text{RPM}}{60}\right)^2}{g}$$ Where
- \$\text{RCF}\$ is "relative centrifugal force", or the force relative to 1 \$g\$; in this case we want this to be \$1\$.
- \$r_\text{m}\$ is the radius of the centrifuge in meters. You can take this, or a similar quantity - for example, taking it in millimeters.
- \$N_\text{RPM}\$ is the rotational speed in revolutions per minute. You're going to output this.
- \$g\$ is the local gravitational field of Earth - for this challenge, use the standard value of \$9.80665\;\text{m}/\text{s}^2\$.
In alternate form, when \$\text{RCF} = 1\$: $$N_\text{RPM} = \dfrac{60\sqrt{\dfrac{g}{r_\text{m}}}}{2\pi}.$$
To clarify: take the radius of the centrifuge, output rotational speed in RPMs, with precision to 6 significant digits. Scoring is standard for code-golf. Test cases (calculated using SpinCalc):
1 -> 29.904167719726267
10 -> 9.456528152601877
50 -> 4.229087956071661
87 -> 3.206063305621029
100 -> 2.9904167719726273
103 -> 2.946545199338184
167 -> 2.314053973112157
200 -> 2.1145439780358304
224 -> 1.9980562507828685
250 -> 1.8913056305203755
264 -> 1.8404742955585696
300 -> 1.726517928287568
328 -> 1.651181438643768
400 -> 1.4952083859863137
409 -> 1.4786659280153986
1000 -> 0.9456528152601877
2000 -> 0.6686775183186282
10000 -> 0.2990416771972627