Question

Example 4 Four particles of equal masses M move
along a circle of radius R under the action of their mutual
gravitational attraction. Find the speed of each particle.​

Answer 1

Answer:

I'm adding the solution page here as there are four particles of masses m.

Since the four particles are moving on the circular path only as a result of each other’s gravitation, it indicates that the net pull on any particle must be acting through the centre of the circle. Such a situation can only occur if the four particles are at the vertices of a square. The four vertices of the square are on the circle. The figure goes something like this: