Presentation on theme: "Bernoulli’s Principle eTo understand Bernoulli’s Principle, think about what happens when a a fluid such as air or water moves. eThink about what happens."— Presentation transcript:
Bernoulli’s Principle eTo understand Bernoulli’s Principle, think about what happens when a a fluid such as air or water moves. eThink about what happens if you hold a plastic spoon in a stream of running water. eYou might predict that the spoon would be pushed away by the water. But it is not. Surprisingly, the spoon is pushed toward the stream of water. The behavior of the spoon demonstrates Bernoulli’s Principle.
Daniel Bernoulli eThe Swiss scientist Daniel Bernoulli found that the faster a fluid moves, the less pressure the fluid exerts. eBernoulli’s principle states that the pressure exerted by a moving stream of fluid is less than the pressure of the surrounding fluid. eThe water running along the spoon is moving but the air on the other side of the spoon is not. eThe moving water exerts less pressure than the still air. eThe result is that the greater pressure of the still air on one side of the spoon pushes the spoon into the stream of water.
Another Example eIf you blow above a sheet of tissue paper, the paper rise. eMoving air blown over the tissue paper, the paper will rise. eMoving air blown over the tissue paper exerts less pressure than the still air blown the paper. eThe greater pressure below the paper pushes it upward.
Objects in Flight eBernoulli’s principle is one factor that can help explain flight - from a small bird to a huge airplane. eObjects can be designed so that their shapes cause air to move at different speeds above and below them. eIf air moves faster above the object, pressure pushes the object upward. eBut if air moves faster below the object, pressure pushes it downward.
Bernoulli’s Principle at Home eBernoulli’s principle can help you understand many common occurrences. eFor example, you can sit next to a fireplace enjoying a cozy fire thanks in part to Bernoulli’s principle. eSmoke rises up the chimney partly because hot air rises, and partly because it is pushed. eWind blowing across the top of the chimney lowers the air pressure there. eThe higher pressure at the bottom then pushes air and smoke up the chimney.
Take a look… eTurn to page 99 and lets read Exploring Wings and how Bernoulli’s principle helps explain how air moving around a wing produces a force.
Figure 20 eTurn to page 100 and lets read how Bernoulli’s principle helps us understand how an atomizer works.