CONCEPTUAL PHYSICS Liquids

Pressure in a liquid A liquid exerts forces against the walls and bottom of a container. Pressure= force area The pressure of a liquid is the weight of the liquid divided by the area. The weight of a liquid depends on its density. The pressure of a liquid at rest depends only on the density and the depth of the liquid. Pressure= density x g x height

The pressure does not depend on the amount of liquid. The pressure of the liquid is the same at any given depth below the surface, regardless of the shape of the container.

Within a liquid, the forces that produce pressure are exerted equally in all directions. When a liquid is pressing against a surface, there is a net force perpendicular to the surface.(Liquid escaping from a hole initially moves perpendicular to the surface.)

Buoyancy: apparent loss of weight of objects when submerged in a liquid. Water exerts an upward force opposite to the direction of gravity called buoyant force. If the weight of a submerged object is greater than the buoyant force, the object will sink. If it is the equal, the object will remain at any level (like a fish) If the weight is less than the buoyant force, the object will float.

A completely submerged object always displaces a volume of liquid equal to its own volume. (Used to calculate the volume of irregularly shaped objects) Archimedes Principle An immersed (partially or completely submerged) object is buoyed up by a force equal to the weight of the fluid it displaces. The weight of the displaced water (not the weight of the submerged object) is the buoyant force.

The effect of density on submerged objects If an object is denser than the fluid in which it is immersed, it will sink. If an object is less dense than the fluid in which it is immersed, it will float. If an ojbect has a density equal to the density of the fluid it is immersed, it will neither sink nor float. To change your density, you must change your mass or your volume.

Flotation: a floating object displaces a weight of fluid equal to its own weight. Ships must be designed to displace weight of water equal to its own weight \\Discovery\E\discovery videos\9th-12th Science\What_Caused_the_Titanic_to_Float__and_then_Sink_.asf

Pascal’s principle: changes in pressure at any point in an enclosed fluid at rest are transmitted undiminished to all point in the fluid and act in all directions. Used in hydraulic presses

CONCEPTUAL PHYSICS Liquids