Four similar particles of mass M are orbiting in a circle of radius r in the same angular direction because of their mutual gravitational attraction, velocity of particle is

Question

$a)\; \bigg[\frac{GM}{r} \bigg(\frac{1+ 2 \sqrt 2}{4}\bigg)\bigg]^{\frac {1}{2}}\\ b)\;3 \sqrt {\frac{GM}{r}} \\ c)\;\sqrt {\frac{GM}{r} (1+ 2 \sqrt 2)} \\ d)\; \bigg[\frac{1}{2} \frac{GM}{r} \bigg(\frac{1+ 2 \sqrt 2}{2}\bigg)\bigg]^{\frac {1}{2}}$

Comments

any body can clear my Doubt...
Why Here force is taken out from
Center of circle

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Because it is the centripetal force