1.

Segment V3.1: Balancing Ball
(Related to Textbook Section 3.2 - F=ma Along a Streamline)

According to the Bernoulli equation, an increase in velocity can cause a decrease in pressure.

The table tennis ball is supported by a jet of air. The net vertical air force is balanced by the ball's weight. If the ball is displaced from the center of the jet, the air velocity past the ball is greater on the side near the jet's center than it is on the side near the jet's edge. Thus, the pressure on the ball is lower near the center, and the ball returns to its stable equilibrium position centered in the air jet.

2.

Segment V3.2: Free Vortex
(Related to Textbook Section 3.3 - F=ma Normal to a Streamline)

For flow with curved streamlines, centrifugal acceleration causes the pressure on the outside of the bend to be greater than on the inside.

The swirling water draining from an inverted bottle approximates a free vortex. The velocity increase and pressure decrease near the center of the flow produce a hollow air core. Similar flows in the atmosphere can produce tornados. The rotation (swirl) of the parent cloud is enhanced as the air is drawn into the strong updraft at the tornado core. Very high winds and low pressure occur near the core, which is made visible by debris and condensed water vapor. (Tornado video courtesy of NOAA National Severe Storm Lab.)

3.

Segment V3.3: Stagnation Point Flow
(Related to Textbook Section 3.5 - Static, Stagnation, Dynamic, and Total Pressure)

On any body in a flowing fluid there is a stagnation point. Some of the fluid flows "over" and some "under" the body. The dividing line (the stagnation streamline) terminates at the stagnation point on the body.

As indicated by the dye filaments in the water flowing past a streamlined object, the velocity decreases as the fluid approaches the stagnation point. The pressure at the stagnation point (the stagnation pressure) is that pressure obtained when a flowing fluid is decelerated to zero speed by a frictionless process.

4.

Segment V3.4: Air Speed Indicator
(Related to Textbook Section 3.5 - Static, Stagnation, Dynamic, and Total Pressure)

The stagnation pressure at the tip of a Pitot tube is greater than the static pressure by an amount equal to one-half times the fluid density times the speed squared. Thus, the speed can be determined by measuring the pressure difference.

The Pitot tube on an aircraft is connected to the air speed indicator, a pressure transducer calibrated to read in knots or miles per hour rather than psi. Because the air density varies with temperature, pressure, and altitude, the speed displayed on the air speed indicator (termed the indicated air speed) equals the actual speed at which the airplane is flying through the air only for standard density conditions.

5.

Segment V3.5: Flow From a Tank
(Related to Textbook Section 3.6.1 - Free Jets)

According to the Bernoulli equation, the velocity of a fluid flowing through a hole in the side of an open tank or reservoir is proportional to the square root of the depth of fluid above the hole.

The velocity of a jet of water from an open pop bottle containing four holes is clearly related to the depth of water above the hole. The greater the depth, the higher the velocity. Similar behavior can be seen as water flows at a very high velocity from the reservoir behind Glenn Canyon dam in Colorado. (Video courtesy of U.S. Bureau of Reclamation.)

6.

Segment V3.6: Venturi Channel
(Related to Textbook Section 3.6.2 - Confined Flows)

As a fluid flows through a converging channel (Venturi channel), the pressure is reduced in accordance with the continuity and Bernoulli equations.

As predicted by the continuity equation, the velocity of air flowing through the channel increases due to the reduction in the channel area. As predicted by the Bernoulli equation, an increase in velocity will cause a decrease in pressure. The attached water columns show that the greatest pressure reduction occurs at the narrowest part of the channel. The same principle is used in a garden sprayer so that liquid chemicals can be sucked from the bottle and mixed with water in the hose.