Chapter 10: Q17Q (page 260)
If you dangle two pieces of paper vertically, a few inches apart (Fig. 10–44), and blow between them, how do you think the papers will move? Try it and see. Explain.
The papers will move towards each other when air is blown in between them.
Over 30 million students worldwide already upgrade their learning with Vaia!
All the tools & learning materials you need for study success - in one app.
Get started for free
Blood is placed in a bottle 1.40 m above a 3.8-cm-long needle, of inside diameter 0.40 mm, from which it flows at a rate of \({\bf{4}}{\bf{.1}}\;{\bf{c}}{{\bf{m}}^{\bf{3}}}{\bf{/min}}\). What is the viscosity of this blood?
A rowboat floats in a swimming pool, and the level of the water at the edge of the pool is marked. Consider the following situations. (i) The boat is removed from the water. (ii) The boat in the water holds an iron anchor which is removed from the boat and placed on the shore. For each situation, the level of the water will,
(a) Rise.
(b) Fall.
(c) Stay the same.
(II) Poiseuille’s equation does not hold if the flow velocity is high enough that turbulence sets in. The onset of turbulence occurs when the Reynolds number, \(Re\) , exceeds approximately 2000. \(Re\) is defined as
\({\mathop{\rm Re}\nolimits} = \frac{{2\overline v r\rho }}{\eta }\)
where \(\overline v \) is the average speed of the fluid, \(\rho \) is its density, \(\eta \) is its viscosity, and \(r\) is the radius of the tube in which the fluid is flowing. (a) Determine if blood flow through the aorta is laminar or turbulent when the average speed of blood in the aorta \(\left( {{\bf{r = 0}}{\bf{.80}}\;{\bf{cm}}} \right)\) during the resting part of the heart’s cycle is about \({\bf{35}}\;{\bf{cm/s}}\). (b) During exercise, the blood-flow speed approximately doubles. Calculate the Reynolds number in this case, and determine if the flow is laminar or turbulent.
Why does the canvas top of a convertible bulge out when the car is traveling at high speed? [Hint: The windshield deflects air upward, pushing streamlines closer together.]
Water at a gauge pressure of \({\bf{3}}{\bf{.8}}\;{\bf{atm}}\) at street level flows into an office building at a speed of \({\bf{0}}{\bf{.78}}\;{\bf{m/s}}\) through a pipe \({\bf{5}}{\bf{.0}}\;{\bf{cm}}\)in diameter. The pipe tapers down to \({\bf{2}}{\bf{.8}}\;{\bf{cm}}\) in diameter by the top floor, \({\bf{16}}\;{\bf{m}}\) above (Fig. 10–53), where the faucet has been left open. Calculate the flow velocity and the gauge pressure in the pipe on the top floor. Assume no branch pipes and ignore viscosity.
Figure 10-53
What do you think about this solution?
We value your feedback to improve our textbook solutions.
