The two moving particles collide and clump together on a smooth horizontal surface. The following statements are given below:

Explanation

The following is the solution: B's statement is correct. In an isolated system, where no external forces are acting, the total energy of the system is conserved. This includes all forms of energy, such as kinetic energy, potential energy, and any other forms present in the system. During the collision and clumping process, if there are no external forces or energy losses to other forms (such as heat or sound), the total energy of the system will remain constant. D's statement is also correct. Since the particles are clumping together on a smooth horizontal surface, no external force is doing work on the system. However, as the particles come together and form a single clumped object, there is an internal force acting between them that brings them closer. Since this force acts in the opposite direction to the displacement, the work done by the system (the internal force) is negative. This negative work is equal in magnitude but opposite in sign to the positive work done by an external force in the opposite direction. It is obvious for the 2-mass system, whether it is elastic, inelastic, or perfectly elastic. The total energy of the system will remain conserved. But the final kinetic energy will be less than the initial K.E. So work done by the system will be negative.