why and how liquid flows?

Answer 1

liquid flows if something (gravity, a pump, or whatever) is pushing on it.

Answer 2

There are two forces involve in flowing.
1. There are forces between the molecules called intermolecular forces.
2. Gravity pulls all of the molecules downwards.

If intermolecular forces are very strong, the object will be a solid and it won't flow, if they are less strong they can remain in contact, but the molecules will move closer to the ground which is what you would call flowing.
If the intermolecular forces are really weak then you would have a gas, which still will flow if it is of a different density than the atmosphere it is in. In my class I pour flammable gas down a ramp into a candle and you can see the path of it jump back towards the flask.

Answer 3

How : In fluid physics, flow of liquid is in streams or layers ( due to viscous drag caused by friction between the layers). If the layers are parallel to each other, flow is linear. If not, flow is turbulent. Linear or turbulent is determined by Reynold's number. Rn < 2000 is linear flow. Rn > 3000 is increasing turbulence. Above 10,000, flow is completely turbulent.

Why : Flow of liquid or any fluid is governed by the Bernoulli's theorem, which states that total energy at any pt. of a flowing liquid is always constant. Henceforth, when a liquid possess some potential energy due to some height & it's height is reduced lated, the P.E. gets converted to kinetic energy, causing a flow.

Answer 4

Liquids, have no definite shape but will take the shape of their container by spreading out their molecules.
A liquid at a high elevation or a high pressure, will flow to a lower elevation or pressure due to the mobility of its molecules.

Answer 5

the molicules are loosely packed