A significant part of aeronautical science is a branch of dynamics called aerodynamics, which deals with the motion of air and the way that it interacts with objects in motion, such as an aircraft.
When you pour a liquid from one container to another, the liquid takes the shape of the container. The volume of the liquid is the same. The properties that solids and liquids share are that they both have definite volume.
All substances can exist in the solid state, although some require a much colder temperature for this to be possible. The different solids can vary significantly in their physical properties (melting point, solubility in different solvents, conductivity in the solid and liquid states, density, malleability etc). It is important to realise that all substances can be categorised into four major groups and that the properties within each group are very similar.