A rubber hose is attached to a funnel, and the free end is bent around to point upward. Water that is poured into the funnel rises in the hose to the same level as in the funnel, even though the funnel has a lot more water in it than the hose. Why? It’s simplest to answer this in terms of Bernoulli’s equation. To understand it conceptually, you may want to review the derivation of Bernoulli’s equation we did in lecture. We used energy conservation.
Young and Freedman 14-9:
An electrical short cuts off all power to a submarine when it is 50 m below the surface of the ocean. The crew must push out a hatch of area 0.80 m3 and weight 300 N on the bottom to escape. If the pressure inside is 1.0 atm, what downward force must they exert on the hatch to open it?
In hot-air ballooning, a large balloon is filled with air heated by a gas burner at he bottom. Why must the air be heated? How does the balloonist control ascent and descent?
A piece of iron is glued to the top of a block of wood. When the block is placed in a bucket of water with the iron on top, the block floats. The block is now turned over so that the iron is submerged beneath the wood. Does the block float or sink? Does the water level in the bucket rise, drop, or stay the same? Explain your answers.
A cubical block of wood 10.0 cm on a side floats at the interface between large volumes of oil and water with its lower surface 2.0 cm below the interface. The density of the oil is 750 kg/m3. What is the mass of the block?
Young and Freedman 14-37:
Air streams horizontally past a small airplane’s wings such that the speed is 70.0 m/s over the top surface and 50.0 m/s past the bottom surface. If the plane has a mass of 700 kg and a wing area of 9.00 m2, what is the net vertical force (including the effects of gravity) on the airplane? The density of the air is 1.20 kg/m3.
Some carpenters level foundations of long buildings by filling a garden hose with glass tubes (10-12 inches long) thrust in the ends. The theory is that the water will be the same height in each of the glass tubes. Suppose there is a small air bubble in the hose. Will this effect the reading from one end to the other or will it cause inaccuracies? Refer to figure 14-49 on page 459 of the text.