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Give an example of entrainment not mentioned in the text.

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Many entrainment devices have a constriction, called a Venturi, such as shown in [link] . How does this bolster entrainment?

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Figure shows a venturi tube, a cylindrical tube broader at both the ends and narrow in the middle. The narrow part is labeled as venturi constriction. The flow of fluid is shown as horizontal arrows along the length of the tube toward the right. The flow lines are closer in the center and spread apart at both the ends. There is an opening on the top portion of the narrow section for the entrained fluid to enter.
A tube with a narrow segment designed to enhance entrainment is called a Venturi. These are very commonly used in carburetors and aspirators.

Some chimney pipes have a T-shape, with a crosspiece on top that helps draw up gases whenever there is even a slight breeze. Explain how this works in terms of Bernoulli’s principle.

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Is there a limit to the height to which an entrainment device can raise a fluid? Explain your answer.

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Why is it preferable for airplanes to take off into the wind rather than with the wind?

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Roofs are sometimes pushed off vertically during a tropical cyclone, and buildings sometimes explode outward when hit by a tornado. Use Bernoulli’s principle to explain these phenomena.

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Why does a sailboat need a keel?

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It is dangerous to stand close to railroad tracks when a rapidly moving commuter train passes. Explain why atmospheric pressure would push you toward the moving train.

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Water pressure inside a hose nozzle can be less than atmospheric pressure due to the Bernoulli effect. Explain in terms of energy how the water can emerge from the nozzle against the opposing atmospheric pressure.

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A perfume bottle or atomizer sprays a fluid that is in the bottle. ( [link] .) How does the fluid rise up in the vertical tube in the bottle?

A perfume bottle with a spray cap.
Atomizer: perfume bottle with tube to carry perfume up through the bottle. (credit: Antonia Foy, Flickr)

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If you lower the window on a car while moving, an empty plastic bag can sometimes fly out the window. Why does this happen?

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Problems&Exercises

Verify that pressure has units of energy per unit volume.

P = Force Area , ( P ) units = N/m 2 = N m/m 3 = J/m 3 = energy/volume alignl { stack { size 12{P= { {"Force"} over {"Area"} } ,} {} #size 12{ \( P \) rSub { size 8{"units"} } ="N/m" rSup { size 8{2} } =N cdot "m/m" rSup { size 8{3} } ="J/m" rSup { size 8{3} } } {} # ="energy/volume" {}} } {}

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Suppose you have a wind speed gauge like the pitot tube shown in [link] (b). By what factor must wind speed increase to double the value of h size 12{h} {} in the manometer? Is this independent of the moving fluid and the fluid in the manometer?

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If the pressure reading of your pitot tube is 15.0 mm Hg at a speed of 200 km/h, what will it be at 700 km/h at the same altitude?

184 mm Hg

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Calculate the maximum height to which water could be squirted with the hose in [link] example if it: (a) Emerges from the nozzle. (b) Emerges with the nozzle removed, assuming the same flow rate.

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Every few years, winds in Boulder, Colorado, attain sustained speeds of 45.0 m/s (about 100 mi/h) when the jet stream descends during early spring. Approximately what is the force due to the Bernoulli effect on a roof having an area of 220 m 2 size 12{"220"`m rSup { size 8{2} } } {} ? Typical air density in Boulder is 1 . 14 kg/m 3 size 12{1 "." "14"`"kg/m" rSup { size 8{3} } } {} , and the corresponding atmospheric pressure is 8 . 89 × 10 4 N/m 2 size 12{8 "." "89" times "10" rSup { size 8{4} } `"N/m" rSup { size 8{2} } } {} . (Bernoulli’s principle as stated in the text assumes laminar flow. Using the principle here produces only an approximate result, because there is significant turbulence.)

2 . 54 × 10 5 N size 12{2 "." "54" times "10" rSup { size 8{5} } " N"} {}

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(a) Calculate the approximate force on a square meter of sail, given the horizontal velocity of the wind is 6.00 m/s parallel to its front surface and 3.50 m/s along its back surface. Take the density of air to be 1.29 kg /m 3 size 12{1 "." "29"`"kg/m" rSup { size 8{3} } } {} . (The calculation, based on Bernoulli’s principle, is approximate due to the effects of turbulence.) (b) Discuss whether this force is great enough to be effective for propelling a sailboat.

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(a) What is the pressure drop due to the Bernoulli effect as water goes into a 3.00-cm-diameter nozzle from a 9.00-cm-diameter fire hose while carrying a flow of 40.0 L/s? (b) To what maximum height above the nozzle can this water rise? (The actual height will be significantly smaller due to air resistance.)

(a) 1 . 58 × 10 6 N/m 2 size 12{1 "." "58" times "10" rSup { size 8{6} } " N/m" rSup { size 8{2} } } {}

(b) 163 m

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(a) Using Bernoulli’s equation, show that the measured fluid speed v for a pitot tube, like the one in [link] (b), is given by

v = 2 ρ gh ρ 1 / 2 , size 12{v= left ( { {2 { {ρ}} sup { ' }gh} over {ρ} } right ) rSup { size 8{ {1} slash {2} } } } {}

where h size 12{h} {} is the height of the manometer fluid, ρ size 12{ { {ρ}} sup { ' }} {} is the density of the manometer fluid, ρ size 12{ρ} {} is the density of the moving fluid, and g size 12{g} {} is the acceleration due to gravity. (Note that v size 12{v} {} is indeed proportional to the square root of h size 12{h} {} , as stated in the text.) (b) Calculate v size 12{v} {} for moving air if a mercury manometer’s h size 12{h} {} is 0.200 m.

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Questions & Answers

what is heat
John Reply
Heat is a form of energy where molecules move
saran
Can you please help me with some questions
Janet Reply
topic-- question
Salman
I know this is unrelated to physics, but how do I get the MCQs and essay to work. they arent clickable.
Jake Reply
20cm3 of 1mol/dm3 solution of a monobasic acid HA and 20cm3 of 1mol/dm3 solution of NaOH are mixed in a calorimeter and a temperature rise of 274K is observed. If the heat capacity of the calorimeter is 160J/K, calculate the enthalpy of neutralization of the acid.(SHCw=4.2J/g/K) Formula. (ms*cs+C)*T
Lilian Reply
why is a body moving at a constant speed able to accelerate
Lilian Reply
20cm3 of 1mol/dm3 solution of a monobasic acid HA and 20cm3 of 1mol/dm3 solution of NaOH are mixed in a calorimeter and a temperature rise of 274K is observed. If the heat capacity of the calorimeter is 160J/K, calculate the enthalpy of neutralization of the acid.(SHCw=4.2J/g/K) Formula. (ms*cs+C)*T
Lilian
because it changes only direction and the speed is kept constant
Justice
Why is the sky blue...?
Star Reply
It's filtered light from the 2 forms of radiation emitted from the sun. It's mainly filtered UV rays. There's a theory titled Scatter Theory that covers this topic
Mike
A heating coil of resistance 30π is connected to a 240v supply for 5min to boil a quantity of water in a vessel of heat capacity 200jk. If the initial temperature of water is 20°c and it specific heat capacity is 4200jkgk calculate the mass of water in a vessel
fasawe Reply
A thin equi convex lens is placed on a horizontal plane mirror and a pin held 20 cm vertically above the lens concise in position with its own image the space between the undersurface of d lens and the mirror is filled with water (refractive index =1•33)and then to concise with d image d pin has to
Azummiri Reply
Be raised until its distance from d lens is 27cm find d radius of curvature
Azummiri
what happens when a nuclear bomb and atom bomb bomb explode add the same time near each other
FlAsH Reply
A monkey throws a coconut straight upwards from a coconut tree with a velocity of 10 ms-1. The coconut tree is 30 m high. Calculate the maximum height of the coconut from the top of the coconut tree? Can someone answer my question
Fatinizzah Reply
v2 =u2 - 2gh 02 =10x10 - 2x9.8xh h = 100 ÷ 19.6 answer = 30 - h.
Ramonyai
why is the north side is always referring to n side of magnetic
sam Reply
who is a nurse
Chilekwa Reply
A nurse is a person who takes care of the sick
Bukola
a nurse is also like an assistant to the doctor
Gadjawa
explain me wheatstone bridge
Malik Reply
good app
samuel
Wheatstone bridge is an instrument used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component.
MUHD
Rockwell Software is Rockwell Automation’s "Retro Encabulator". Now, basically the only new principle involved is that instead of power being generated by the relative motion of conductors and fluxes, it’s produced by the modial interaction of magneto-reluctance and capacitive diractance. The origin
Chip
what refractive index
Adjah Reply
write a comprehensive note on primary colours
Harrison Reply
relationship between refractive index, angle of minimum deviation and angle of prism
Harrison
Practice Key Terms 2

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Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
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