If there are no external forces, the centre of mass of a double star moves like a free particle. If we go to the centre of mass frame, then we find that the two starts are moving in a circle about the centre of mass, which is at rest.

If there are no external forces, the centre of mass of a double star m

1.	If there are no external forces, the centre of mass of a double star moves like a free particle. If we go to the centre of mass frame, then we find that the two starts are moving in a circle about the centre of mass, which is at rest.
Answer» If both assertion and reason are true and reason is the correct explanation of assertion. If both assertion and reason are reason are true but reason is not the correct explanation of assertion. If assertion is true but reason is false If both assertion and reason are false. Solution :(b) In our frame of reference, the TRAJECTORIES of the starts are a combination of (i) Uniform motion in a STRAIGHT LINE of the centre of MASS and. (ii) circular ORBITS of the starts about the centre of mass.