Forces in Fluids

Section 1: Pressure Section 2: Floating and Sinking Section 3: Pascal’s Principle Section 4: Applying Bernoulli’s Principle

Pressure

Pressure Pressure - the force exerted on a surface divided by the area over which the force is exerted.

Pressure Which type of shoe exerts more pressure on the surface?

Calculating Pressure

Fluid Pressure Fluid - substance that can easily flow. All of the forces exerted by the individual molecules in a fluid add together to make up the pressure exerted by the fluid.

Atmospheric Pressure Because air has mass, gravity acts on all of the air molecules in our atmosphere, creating tremendous pressure at sea level. The pressure inside our bodies balances the pressure outside our bodies, so we don’t feel a thing!

Variations in Fluid Pressure Air pressure decreases as elevation increases. Water pressure increases as depth increases.

Fluid pressure precautions Oxygen masks in cabin of airplane, necessary to breathe if the cabin becomes depressurized. Newt suit - designed to hold up under intense pressures of the deep sea

Floating or Sinking Why do some things in the ocean float but others sink?

Floating and Sinking: Archimedes’ Principle Archimedes Principle virtual lab

Buoyancy Buoyant Force - force that water exerts on submerged objects Acts against gravity and makes objects feel lighter

Controlling Buoyancy

Density

Density The density of pure water is 1g/cm3 Pine Oak Cedar

Buoyancy: A Powerful Force!

Pascal’s Principle Pascal’s Principle - When a force is applied to a confined fluid, the change in pressure is transmitted equally to all parts of the fluid.

Examples of Pascal’s Principle in Real World

More Examples of Pascal’s Principle in Real World

Hydraulic Systems FORCE IS MULTIPLIED LARGER AREA

Hydraulic Systems

Hydraulic Brakes

Bernoulli Predictions Lab

Bernoulli’s Principle Bernoulli’s Principle - As the speed of a moving fluid increases, the pressure within the fluid decreases. Faster fluid = less pressure

Bernoulli’s Principle at Work

Bernoulli’s Principle at Work

Bernoulli’s Principle at Work