When you knock on a door, what causes you to hear a sound?

what is the answer

vibrations

Explanation:

When you strike the wood, energy is transferred from the finger to the wood. Some energy is lost during impact. The rest energy travels to the opposite end in the form of vibrations. At the opposite end wood starts vibrating and the air on the suface as well.

in an absolute  monarchy, the  monarchrules as an autocrat, with absolutepower  over the state and government — for example, the right to rule by decree, promulgate laws, and impose punishments. the  monarch isnominally sovereign but the electorate, through their legislature, exercise political sovereignty.

citizens were able to charge more for their goods and services