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Tuesday, June 15, 2010

UNDERSTANDING PRESSURE IN LIQUIDS

A liquid in a container exerts pressure because of its weight.
For example, if you try to put your finger over the end of a tap when it is turned on, you can feel the pressure of the water in the pipe.

If a fluid (liquid or gas) has a density ρ, its pressure P, at a point due to the fluid of height h, is given by
P = ρgh where g = gravitational acceleration

Therefore, for a given liquid, its pressure:
i. increases with depth
ii. increases with density


For a given point in the fluid, its pressure acts equally in all directions.
It does not depend on the shape of containers, only on its depth.


Quiz:
Example 1
If the density of sea water is 1150 kgm-3, calculate the pressure below 40m of sea water due to the water alone.

3 comments:

  1. very good, but i had no idea... what does it means "deep water"?

    ReplyDelete
  2. p=hpg
    =40x1150x10
    = 46 kPa
    more than 46 kPa!!
    M i correct???

    ReplyDelete
  3. p= hpg
    = 40x1150x10
    = 460 000 Pa
    = 460 kPa

    ReplyDelete

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