1. Liquids

2. Pressure
The pressure that a block exerts on a table is simply the weight of the block divided by its area of contact.

3. Pressure in Liquid Liquid pressure = weight density X depth
Note: Total pressure would also include atmospheric pressure (101.3kPa).
Water pressure depends on depth and not on volume.
At any point within a liquid, the forces that produce pressure are exerted equally in all directions.

4. Pressure in Liquid
Liquid pressure = weight density X depth

5. Pressure in Liquid Liquid pressure = weight density X depth 3 m 6 m
The surface that must withstand the greater pressure is the surface with the deepest water behind it, not the most water.

6. Aquaducts

7. Liquid Pressure

8. Liquid Pressure
The forces in a liquid that produce pressure against a surface add up to a net force that is perpendicular to the surface.

9. Liquid Pressure
Liquid escaping through a hole initially moves perpendicular to the surface.

10. Buoyancy Buoyant Force = weight of the water displaced
(net upward force, opposite in direction to gravity)
The submerged object’s volume, not its weight determines buoyant force.

11. Buoyancy 3kg 0kg 1kg 2kg Buoyant Force = weight of the water displaced
What is the buoyant force in Newtons?
Recall that the mass of 1 L of water =1kg
1 kg = 9.8 N

12. Displacement
Determining Volume

13. Displacement
Determining Volume

14. Displacement
Determining Volume
Water Displaced

15. Density What makes an object sink or float?
What about the density of the fluid?

16. Does it sink, or does it float?
An object more dense than the fluid in which it is immersed sinks.
An object less dense than the fluid in which it is immersed floats.
An object equal to the density of the fluid in which it is immersed neither sinks nor floats. (Think of fish.)

17. Archimedes’ Principle
An immersed body is buoyed up by a force equal
to the weight of the fluid it displaces
The volume of displaced water is the same at any depth.
Note: Any object with a volume of 1 L will experience a buoyant force of 9.8 N when fully submerged in water.

18. Archimedes’ Principle
An immersed body is buoyed up by a force equal
to the weight of the fluid it displaces
What about the density of the liquid?
Principle of Flotation—A floating object displaces a weight of
fluid equal to its own weight.

19. Pascal’s Principle
A change in pressure at any point in an enclosed fluid at rest
is transmitted undiminished to all points in the fluid.

20. Pascal’s Principle
A change in pressure at any point in an enclosed fluid at rest
is transmitted undiminished to all points in the fluid.
500kg
10kg
50 times the area = 50 times the force

21. Pascal’s Principle
A change in pressure at any point in an enclosed fluid at rest
is transmitted undiminished to all points in the fluid.
500kg
10kg
Input force X distance = Output force X distance

22. Pascal’s Principle

23. Pascal’s Principle

24. Surface Tension
The contractive tendency of the surface of liquids

25. Surface Tension Liquid surfaces tend to contract to the shape
with the least
surface area

26. Capillarity Adhesion—attraction between unlike substances
Cohesion—attraction between like substances