Question

what do you understand by collision?

Answer 1

Collision means the striking of two object results in the change in the shape or size.

Answer 2

A collision is an event in which two or more bodies exert forces on each other for a relatively short time. Although the most common colloquial use of the word "collision" refers to incidents in which two or more objects collide with great force, the scientific use of the word "collision" implies nothing about the magnitude of the force.