Two particles of equal mass m move in a circle of radius r under the action of their mutual gravitational attraction. The speed of each particle will be:
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Two particles of equal mass m move in a circle of radius r under the action of their mutual gravitational attraction. The speed of each particle will be:

G1 Physics · Accepted Answer

The separation between particles is 2r. Gravitational force on each is Gm²/(2r)² = Gm²/(4r²). This provides centripetal force mv²/r. Hence mv²/r = Gm²/(4r²), giving v = √(Gm/4r).