Question

Why do planets do not collide while revolving around the sun?

Answer 1

Answer:

The planets all formed from this spinning disk-shaped cloud, and continued this rotating course around the Sun after they were formed. The gravity of the Sun keeps the planets in their orbits. They stay in their orbits because there is no other force in the Solar System which can stop them.

Answer 2

Answer:

The simple answer is that their free-fall orbits are in lock with the sun (or more specifically, the solar system's center of gravity, which happens to be in the sun). Unless if the sun's gravity changed for whatever reason or if something happened to the acceleration & impacted free-fall, the planets will not collide.