In a situation involving conservation of momentum, if two bodies collide elastically, what physical quantity remains constant?

In an elastic collision, the key principle at play is the conservation of momentum. This means that the total momentum of the system before the collision is equal to the total momentum of the system after the collision. Momentum, defined as the product of an object's mass and its velocity, is a vector quantity.

In an isolated system where no external forces are acting, momentum remains constant throughout the collision. This conservation holds true regardless of the nature of the forces acting at the point of impact, whether they are elastic or inelastic.

While kinetic energy is also conserved in elastic collisions, which is potentially a source of confusion, the critical takeaway regarding momentum is that it is always conserved in such scenarios. The idea of constant force and acceleration does not apply to the process of the collision itself; they can vary throughout the interaction.

Thus, the conservation of momentum is the fundamental principle that ensures the total momentum before and after the collision remains constant.