Pressure in fluids and Pascal's law.

[harjyot]

I have a lot of confusion and I hope someone can help me in clearing my doubts.
considering a right cylindrical container with a liquid filled in ,if we take two points, y1 and y2(near the bottom)

1) first of all I thought that pressure inside a fluid arose because of the weight of the fluid column and it was always in the downward direction.but now I find it's in the upward direction too? (is this only when an object is introduced?!)

2) does the Pascal's law that pressure at any point in a fluid is same, work only when the weight of the fluid column is not considered right?

3)if I have a container with some liquid and a piston on the top, I attach another parallel cylinder to it's side with a piston. now when I push the first piston, shouldn't the pressure move only in the downward direction? but we see that it travels sideways and pops the other piston out. how?

 

[A.T.]

1) first of all I thought that pressure inside a fluid arose because of the weight of the fluid column and it was always in the downward direction.but now I find it's in the upward direction too? (is this only when an object is introduced?!)

The force of pressure at any point acts equally in all directions.

2) does the Pascal's law that pressure at any point in a fluid is same, work only when the weight of the fluid column is not considered right?

No. The Law includes the pressure from weight of the fluid column:
http://en.wikipedia.org/wiki/Pascal's_law#Definition

3)if I have a container with some liquid and a piston on the top, I attach another parallel cylinder to it's side with a piston. now when I push the first piston, shouldn't the pressure move only in the downward direction? but we see that it travels sideways and pops the other piston out. how?

See 1)