Q. Two particles and initially at rest, move towards each other, under mutual force of attraction. At an instance when the speed of is and speed of is , the speed of center of mass is

 8267  203 BITSATBITSAT 2008 Report Error

Solution:

As initially both the particles were at rest therefore velocity of centre of mass was zero and there is no external force on the system so speed of centre of mass remains constant i.e., it should be equal to zero.