Why did Tomb-Sweeping Day set off firecrackers to worship his ancestors?

The above answer is one-sided. Let me say:

This is a custom that has gradually formed. The tools of ancient people were not strong enough, and wild animals often hurt people. In addition, some phenomena (such as phosphorus fire) can't be explained by people. People are very small to nature, so natural and man-made disasters are inevitable, so people believe in ghosts and gods.

Firecrackers were called firecrackers at that time, that is, they were lit with bamboo in the fire, and the internal gas expanded and eventually exploded.

However, wild animals are afraid of these noises, so people learn to use firecrackers to scare wild animals and protect themselves. People gradually think that it can be used to exorcise ghosts, and wizards also use it to practice, so they have to shoot.

Now that people believe in science, the original intention of shooting has faded, replaced by a festive meaning, and there is a saying of salute.

Shooting at ancestor worship is a manifestation of reverence for ancestors.

My answer is over, for reference only, I hope there will be a better answer.