Two charged particles of masses m and 2m are placed distane d apart on a smooth horizontal table. Because of their mutual attraction, they move towards each other and collide. Where will the collision occure with respect to the initial positions?

Explanation

If we consider both the particles in a single system then electric force of attraction becomes internal force of the system and there is no other force acting on this system in horizontal direction. Hence ncceleration of centre of mass of the system is zero in the horizontal direction. Particles are released from the state of rest hence initial velocity of the centre of mass is vero. As we have understood that initial velocity of the centre of Mass is zero and acceleration is also zero in the horizontal direction hence centre of mass remains at rest during the process. So finally both the particles will collide at the initial location of centre of mass. Initial distance of centre of mass from m can be calculated as follows:
`x=(mxx0+2mxxd)/(m+2m=(2d)/(3)`
So we can understand that collision between particles occurs at a distance 2d/3 from initial position of particle of mass m.