Ch. 11 Forces in Fluids

Pressure• Pressure-force per unit area on a surface• Unit of measurement: pascal (Pa): 1 N/m2

• A fluid is any substance that can easily flow-liquids and gases

Fluid Pressure• The particles of a fluid are in constant motion• All of the forces exerted by the individual

molecules in a fluid added together make up fluid pressure

Balanced Pressures• We don’t feel

“crushed” by the atmosphere because the pressure is balanced with the pressure your body is exerting outward

Variations in Fluid Pressure

• Pressure and elevationAir pressure decrease as elevation increases

Variations in Fluid Pressure

• Pressure and depthWater pressure increases as depth increases

Pascal’s Principal

• When force is applied to a confined fluid, an increase in pressure is transited equally to all parts of the fluid

Floating and Sinking

Buoyancy Force- acts in the upward direction, against the force of gravity, so it makes an object feel lighter

Archimedes’ Principle

The buoyant force of an object is equal to the weight of the fluid displaced by the object

Bernoulli’s Principle

The pressure exerted by a moving stream of fluid is less than the pressure of the surrounding fluid

Bernoulli’s Principle