Fluid Mechanics: Liquids, Pressure, Buoyancy, and Pascal's Principle

What is the defining characteristic of the liquid phase?

Molecules can flow freely from position to position by sliding over one another.

What determines the pressure of a liquid at rest?

Gravity, density, and depth of the liquid.

How is pressure defined?

Pressure is defined as the force per unit area on which the force acts; pressure = force/area.

What is the equation for pressure created by a liquid?

Pressure due to liquid = density × g × depth.

Does liquid pressure depend on the amount of liquid?

No, liquid pressure does not depend on the amount, volume, or weight of the liquid.

How is pressure exerted within a liquid?

At any point within a liquid, forces that produce pressure are exerted equally in all directions.

What happens when the weight of a submerged object is greater than the buoyant force?

The object will sink.

What is buoyancy?

The apparent loss of weight of objects when submerged in a liquid.

What is the buoyant force?

The net upward force exerted by a fluid on a submerged or immersed object.

What occurs when the weight of a submerged object equals the buoyant force?

The submerged object will remain at any level.

What does Archimedes' principle state?

The buoyant force on an immersed object is equal to the weight of the fluid it displaces.

What is the relationship between buoyancy and displaced liquid?

Archimedes' principle describes this relationship and is true for both liquids and gases.

What are the three rules for sinking and floating?

1. An object more dense than the fluid sinks. 2. An object less dense than the fluid floats. 3. An object with equal density neither sinks nor floats.

What does the principle of flotation state?

A floating object displaces a weight of fluid equal to its own weight.

What happens to a ship when it is loaded?

It floats lower in the water.

What is Pascal's principle?

Changes in pressure at any point in an enclosed fluid at rest are transmitted undiminished to all points in the fluid and act in all directions.

Who discovered Pascal's principle?

Blaise Pascal.

How does a hydraulic press utilize Pascal's principle?

Any additional pressure is exerted against every square centimeter of the larger piston.

What is the SI unit of pressure named after Blaise Pascal?

Pascal (Pa).

What is the effect of a submarine displacing a weight of water greater than its own weight?

It will rise.

What is the effect of a submarine displacing less weight of water than its own weight?

It will go down.

What happens when a submarine displaces exactly its weight of water?

It will remain at constant depth.