lecture 8- fluid dynamics chapter 14 - …jn511/lectures/lecture8slides.pdf · lecture 8- fluid...

Exam 2 Fluids Fluids at Rest Pascal’s Principle Archimedes Fluids in motion Questions

Lecture 8- Fluid DynamicsChapter 14

Prof. Noronha-HostlerPHY-124H HONORS ANALYTICAL PHYSICS IB

Phys- 124HMarch 23rd , 2018

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The Exam 2 practice tests are now on WebAssignunderneath Resources (same location as before)A number of you emailed me regarding Homework 8. Thisis something that I discussed on 03/02/18 in class.Because the test is this weekend, the homework was dueearly to help you prepare ahead of time. It is true wehaven’t discussed it in class yet but it was due to the earlytest date. I plan to get the class notes online by the eveningtoday to help you prepare as well, since chapter 14 will becovered on the test. What I can do is give you one extraday starting after class on Friday to Saturday.The test will once again include its own formula sheet (justlike the first test). This is to ensure that you all have thesame equations andAlso, I ask that all students please bring their owncalculators (not TI-80 types, though).

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Phase of Matter

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Use of Fluid Mechanics

Neutron Star Mergers

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Traffic jam

5 / 14

Biophysics

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Density

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Pressure

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Hydrostatic Pressure

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Measuring Pressure

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Hydraulics

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Archimedes’ Principle

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Continuity Equation

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Bernoulli’s Equation

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14.3.3. What volume of helium (density = 0.179 kg/m3) has the same mass as 5.0 m3 of nitrogen (density = 1.25 kg/m3)?

a) 35 m3

b) 27 m3

c) 7.0 m3

d) 3.5 m3

e) 0.72 m3

14.3.3. What volume of helium (density = 0.179 kg/m3) has the same mass as 5.0 m3 of nitrogen (density = 1.25 kg/m3)?

a) 35 m3

b) 27 m3

c) 7.0 m3

d) 3.5 m3

e) 0.72 m3

14.3.4. A swimmer is swimming underwater in a large pool. The force on the back of the swimmer’s hand is about one thousand newtons. The swimmer doesn’t notice this force. Why not?

a) This force is actually smaller than the force exerted by the atmosphere.

b) The force is large, but the pressure on the back of the hand is small.

c) The force is exerted on all sides equally.

d) The swimmer is pushing on the water with the same force.

e) I do not know, but I’m sure I would feel that kind of force.

14.3.4. A swimmer is swimming underwater in a large pool. The force on the back of the swimmer’s hand is about one thousand newtons. The swimmer doesn’t notice this force. Why not?

a) This force is actually smaller than the force exerted by the atmosphere.

b) The force is large, but the pressure on the back of the hand is small.

c) The force is exerted on all sides equally.

d) The swimmer is pushing on the water with the same force.

e) I do not know, but I’m sure I would feel that kind of force.

14.3.8. Helium gas is confined within a chamber that has a moveable piston. The mass of the piston is 8.7 kg; and its radius is 0.013 m. If the system is in equilibrium, what is the pressure exerted on the piston by the gas?

a) 1.639 × 104 Pa

b) 8.491 × 104 Pa

c) 1.013 × 105 Pa

d) 1.606 × 105 Pa

e) 2.619 × 105 Pa

14.3.8. Helium gas is confined within a chamber that has a moveable piston. The mass of the piston is 8.7 kg; and its radius is 0.013 m. If the system is in equilibrium, what is the pressure exerted on the piston by the gas?

a) 1.639 × 104 Pa

b) 8.491 × 104 Pa

c) 1.013 × 105 Pa

d) 1.606 × 105 Pa

e) 2.619 × 105 Pa

14.4.1. Two dams are identical with the exception that the water reservoir behind dam A extends twice the horizontal distance behind it as that of dam B. Which one of the following statements regarding these dams is correct?

a) The horizontal distance of the water behind the two dams does not determine the force on them.

b) Dam A is more likely to collapse than dam B if the water level rises.

c) Dam B is more likely to collapse than dam A if the water level rises.

d) The force exerted by the water on dam A is greater than that on dam B.

e) The force exerted by the water on dam B is greater than that on dam A.

14.4.1. Two dams are identical with the exception that the water reservoir behind dam A extends twice the horizontal distance behind it as that of dam B. Which one of the following statements regarding these dams is correct?

a) The horizontal distance of the water behind the two dams does not determine the force on them.

b) Dam A is more likely to collapse than dam B if the water level rises.

c) Dam B is more likely to collapse than dam A if the water level rises.

d) The force exerted by the water on dam A is greater than that on dam B.

e) The force exerted by the water on dam B is greater than that on dam A.

14.4.2. You are vacationing in the Rocky Mountains and decide to ride a ski lift to the top of a mountain. As you go up, your feel your ears make a “pop” sound because of changes in atmospheric pressure. Which way does your ear drum move, if at all, during your ascent up the mountain?

a) inward, because the pressure outside the ear is larger than the pressure inside the ear

b) inward, because the pressure outside the ear is smaller than the pressure inside the ear

c) No movement occurs. This is just the sound of air bubbles bursting inside the ear.

d) outward, because the pressure outside the ear is smaller than the pressure inside the ear

e) outward, because the pressure outside the ear is larger than the pressure inside the ear

14.4.2. You are vacationing in the Rocky Mountains and decide to ride a ski lift to the top of a mountain. As you go up, your feel your ears make a “pop” sound because of changes in atmospheric pressure. Which way does your ear drum move, if at all, during your ascent up the mountain?

a) inward, because the pressure outside the ear is larger than the pressure inside the ear

b) inward, because the pressure outside the ear is smaller than the pressure inside the ear

c) No movement occurs. This is just the sound of air bubbles bursting inside the ear.

d) outward, because the pressure outside the ear is smaller than the pressure inside the ear

e) outward, because the pressure outside the ear is larger than the pressure inside the ear

14.4.3. Consider the mercury U-shaped tube manometer shown. Which one of the following choices is equal to the gauge pressure of the gas enclosed in the spherical container? The acceleration due to gravity is g and the density of mercury is .

d) Patm + gb

e) Patm gc

14.4.3. Consider the mercury U-shaped tube manometer shown. Which one of the following choices is equal to the gauge pressure of the gas enclosed in the spherical container? The acceleration due to gravity is g and the density of mercury is .

d) Patm + gb

e) Patm gc

14.5.1. What is the force that causes liquid to move upward in a drinking straw as a person takes a drink?

a) that due to a low pressure region caused by sucking

b) that due to the pressure within the liquid

c) that due to atmospheric pressure

d) that due to the person sucking on the straw

e) that due to friction forces within the straw

14.5.1. What is the force that causes liquid to move upward in a drinking straw as a person takes a drink?

a) that due to a low pressure region caused by sucking

b) that due to the pressure within the liquid

c) that due to atmospheric pressure

d) that due to the person sucking on the straw

e) that due to friction forces within the straw

14.5.2. The height of mercury in one barometer is 0.761 m above the reservoir of mercury. If a second barometer is brought to the same location that has a liquid with a density of 2650 kg/m3, what is the height of the fluid in the second barometer?

a) 0.761 m

b) 2.02 m

c) 2.87 m

d) 5.03 m

e) 3.91 m

14.5.2. The height of mercury in one barometer is 0.761 m above the reservoir of mercury. If a second barometer is brought to the same location that has a liquid with a density of 2650 kg/m3, what is the height of the fluid in the second barometer?

a) 0.761 m

b) 2.02 m

c) 2.87 m

d) 5.03 m

e) 3.91 m

14.6.1. A fluid is completely enclosed in the system shown. As the piston is moved to the right, which one of the following statements is true?

(a) Pushing the piston to the right causes the pressure on the left side of the vertical cylinder to be larger than that on the right side.

(b) Pushing the piston to the right causes the pressure on the bottom of the vertical cylinder to be larger than that on the top.

(c) Pushing the piston to the right causes the pressure throughout the vertical cylinder to increase by the same amount.

(d) Pushing the piston to the right causes the pressure in one part of the vertical cylinder and a corresponding decrease in another part of the cylinder.

(e) After the piston is pushed by a distance s and held in that position, the pressure will be the same at all points within the fluid.

14.6.1. A fluid is completely enclosed in the system shown. As the piston is moved to the right, which one of the following statements is true?

(a) Pushing the piston to the right causes the pressure on the left side of the vertical cylinder to be larger than that on the right side.

(b) Pushing the piston to the right causes the pressure on the bottom of the vertical cylinder to be larger than that on the top.

(c) Pushing the piston to the right causes the pressure throughout the vertical cylinder to increase by the same amount.

(d) Pushing the piston to the right causes the pressure in one part of the vertical cylinder and a corresponding decrease in another part of the cylinder.

(e) After the piston is pushed by a distance s and held in that position, the pressure will be the same at all points within the fluid.

14.6.3. A woman stands on a platform with a diameter D1 that acts as a piston. The combined mass of the woman and the piston is 75 kg. The piston pushes downward on a reservoir of oil that supports a second platform with a diameter D2 on which 12 women are standing. The combined mass of the second platform and the 12 women is 780 kg. Both platforms are at the same height during this demonstration; and they are at rest. What is the ratio D2/D1?

a) 2.4

b) 3.2

c) 4.8

14.6.3. A woman stands on a platform with a diameter D1 that acts as a piston. The combined mass of the woman and the piston is 75 kg. The piston pushes downward on a reservoir of oil that supports a second platform with a diameter D2 on which 12 women are standing. The combined mass of the second platform and the 12 women is 780 kg. Both platforms are at the same height during this demonstration; and they are at rest. What is the ratio D2/D1?

a) 2.4

b) 3.2

c) 4.8

14.7.1. A solid block of mass m is suspended in a liquid by a thread. The density of the block is greater than that of the liquid. Initially, the fluid level is such that the block is at a depth d and the tension in the thread is T. Then, the fluid level is decreased such that the depth is 0.5d. What is the tension in the thread when the block is at the new depth?

a) 0.25T

b) 0.50T

14.7.1. A solid block of mass m is suspended in a liquid by a thread. The density of the block is greater than that of the liquid. Initially, the fluid level is such that the block is at a depth d and the tension in the thread is T. Then, the fluid level is decreased such that the depth is 0.5d. What is the tension in the thread when the block is at the new depth?

a) 0.25T

b) 0.50T

lecture 8- fluid dynamics chapter 14 - …jn511/lectures/lecture8slides.pdf · lecture 8- fluid...

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