This document discusses key concepts around liquid pressure, buoyancy, Archimedes' principle, and Pascal's principle. It explains that liquid pressure depends on depth and density but not container shape. The buoyant force equals the weight of fluid displaced. Archimedes' principle states the buoyant force equals the weight of fluid displaced. Pascal's principle explains that pressure changes in an enclosed fluid are transmitted undiminished throughout the fluid.

1. CHAPTER 19

2. LIQUID PRESSURE
• Pressure = Force/Area
• Pressure measured in Pascals, Force in Newtons,
and Area measured in m2
• The pressure of a liquid at rest depends only on
gravity and the density and depth of the liquid
• Density – Mercury 13.6x dense as water =
weighs13.6 x more and exerts 13.6 x more pressure
• Depth - Greater depth = greater pressure

3. LIQUID PRESSURE
• Pressure of liquid at rest does not depend on shape
or size of container.
• Pressure due to a liquid = density x g x depth
• At a given depth, a given liquid exerts the same
pressure against any surface.
• Pressure of a liquid does not depend on volume or
weight.

4. BUOYANCY
• The apparent loss of weight of objects when
submerged in a liquid.
• Submerged boulder = lighter than above water
• Buoyant Force = net upward force exerted by a
liquid on a submerged or immersed object.
• Weight > buoyant force = sinking
• Weight < buoyant force = rise to surface.

5. BUOYANCY
• What happens to the water level when you place a
stone in beaker full of water?
• Correct! The water level will rise!
• Volume of stone submerged = volume of water
displaced
• ρLead =11.3 g/cm3

6. ARCHIMEDES PRINCIPLE
• Archimedes Principle states that the buoyant force
on an immersed object is equal to the weight the
fluid it displaces.
• It is true for both liquids and gases
• Immersed = partially or completely submerged.
• If we submerged a liter container halfway in the
water, it would be buoyed up by the weight of half
a liter of water.

7. ARCHIMEDES PRINCIPLE
• A 300 gram brick weighs about 3 N in air.
• Suppose it displaces 2 N of water when submerged.
• Buoyant force also = 2N
• The apparent weight of the brick = weight in air –
buoyant force

8. ARCHIMEDES PRINCIPLE
• upward force of water pressure on the bottom of the
brick minus downward force due to water pressure on
top = weight of liquid displaced.
• As long as the block is submerged, depth makes no
difference
• Why?
• There is more pressure at greater depths, but the
difference in pressures in top and bottom is the same

9. FLOTATION
• Iron is ~ 8 times more dense than water.
• 1- ton block of iron in water will displace 1/8 ton of
water.
• Buoyant force does not equal weight of the block
• How do you make an object made of 1 ton of iron
float?
• Reshape it into a bowl to displace greater volume
of water.

10. PASCAL’S PRINCIPLE
• Pascal’s Principle states that changes in pressure at
any given point in an enclosed fluid at rest are
transmitted undiminished to ALL points in the fluid
and act in ALL directions.
• Used in hydraulic lifts.
• Multiplies forces – 1 Newton input 50 Newtons
output