In a catapult, Initially, energy is stored in the form of potential energy which is later converted into kinetic energy.
Potential energy can be stored in the form of elastic potential energy in the case of elastic. It suddenly releases the energy to propel the object into the air.
Pascal's principle, also called Pascal's law, in fluid (gas or liquid) mechanics, statement that, in a fluid at rest in a closed container, a pressure change in one part is transmitted without loss to every portion of the fluid and to the walls of the container.