Yes, physical interaction is necessary for a collision to occur. In the context of classical physics, a collision involves the physical contact or interaction between two or more objects. During a collision, these objects exert forces on each other, resulting in a transfer of momentum and, potentially, a change in their motion or deformation of their shapes.
For example, in a car accident, the collision occurs when two vehicles come into physical contact with each other, causing the forces of impact to be exchanged between them. Similarly, in a game of billiards, the collision between two balls happens when they collide physically, causing a transfer of momentum and a change in their trajectories.
However, it is worth noting that the concept of collision can also be extended to other domains, such as particle physics or computational simulations, where physical contact may not be involved. In these cases, the term "collision" refers to the interaction or interaction energy between particles or simulated entities, even if they do not physically touch.