Normal Pressure

$$ Pressure = \frac{Force [N]}{Area [x^2]} $$

1 N/m^2 = 1 Pa [Pascal]

1 kPa = 1,000 Pa

Pressure In Liquids - Ignore ATMOSPHERIC PRESSURE

  1. Pressure acts in all directions - Liquids pushes on every surface in contact with it, no matter which way the surface is facing.
  2. Pressure increases with depth - Deeper → Greater weight above → Greater pressure
  3. Doesn't depend on shape of the container - If depth is the same, pressure is the same
    1. If a container that is sloping downwards from the top is compared to a normal container, then if the same volume is removed from both, the sloping one’s depth will decrease

$$ Pressure (Liquids) = Density . AccelerationDueToGravity .Height Above $$

Pressure = PGH

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Pressure From Air

Atmospheric Pressure - 100 kPa [100,000 N/m^2]

^ We aren't crushed because the pressure is matched by the blood in our system

Example:

  1. Vacuum Cleaner - Fan lowers the air pressure creating partial vacuum, allowing the atmosphere to rush in, carrying the dust and dirt with it.
  2. Drinking through a straw - You take in air into your body, reducing the air pressure inside the straw, allowing atmospheric pressure to push the liquid upwards