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Questions and Answers
Which of the following is NOT a property of pressure in a fluid?
Which of the following is NOT a property of pressure in a fluid?
- Pressure is transmitted undiminished to all parts of an enclosed fluid.
- At a given depth, pressure is equal in all directions.
- Pressure acts perpendicular to the surface in contact.
- Pressure is only exerted in the direction of gravity. (correct)
According to Pascal's Principle, pressure applied to an enclosed fluid is diminished as it is transmitted throughout the fluid.
According to Pascal's Principle, pressure applied to an enclosed fluid is diminished as it is transmitted throughout the fluid.
False (B)
Explain how Pascal's Principle is utilized in hydraulic systems, providing a real-world example.
Explain how Pascal's Principle is utilized in hydraulic systems, providing a real-world example.
Pascal's Principle is used in hydraulic systems to multiply force. A small force applied to a small area creates pressure that is transmitted to a larger area, resulting in a larger force. An example is a car's braking system.
The pressure at a certain depth in a fluid is dependent on the fluid's density, the depth, and the ______.
The pressure at a certain depth in a fluid is dependent on the fluid's density, the depth, and the ______.
Match the pressure measurement type with its definition:
Match the pressure measurement type with its definition:
What is the primary difference between absolute pressure and gauge pressure?
What is the primary difference between absolute pressure and gauge pressure?
Aneroid barometers use a column of liquid to measure atmospheric pressure.
Aneroid barometers use a column of liquid to measure atmospheric pressure.
Explain how a mercury barometer works and what it measures.
Explain how a mercury barometer works and what it measures.
In the equation $P = P_{atm} + \rho gh$, the term $P_{atm}$ represents ______.
In the equation $P = P_{atm} + \rho gh$, the term $P_{atm}$ represents ______.
Match the following units of pressure to their equivalent Pascal (Pa) value:
Match the following units of pressure to their equivalent Pascal (Pa) value:
Consider a U-tube manometer connected to a vessel containing gas. If the liquid level in the arm connected to the vessel is lower than the level in the open arm, what does this indicate about the pressure in the vessel?
Consider a U-tube manometer connected to a vessel containing gas. If the liquid level in the arm connected to the vessel is lower than the level in the open arm, what does this indicate about the pressure in the vessel?
A Bourdon gauge directly measures volume changes due to pressure.
A Bourdon gauge directly measures volume changes due to pressure.
Describe the principle behind how electronic pressure transducers work.
Describe the principle behind how electronic pressure transducers work.
The typical range of maximum arterial blood pressure in humans is ______ to 19,000 Pa.
The typical range of maximum arterial blood pressure in humans is ______ to 19,000 Pa.
Match the medical instrument to its function:
Match the medical instrument to its function:
Why are pressures in medicine often quoted as heights of mercury (mmHg)?
Why are pressures in medicine often quoted as heights of mercury (mmHg)?
Density is defined as mass times volume.
Density is defined as mass times volume.
Explain the relationship between depth and pressure in a fluid of uniform density. Provide the formula that describes this relationship.
Explain the relationship between depth and pressure in a fluid of uniform density. Provide the formula that describes this relationship.
If atmospheric pressure is 101325 Pa, this is equivalent to approximately ______ kPa.
If atmospheric pressure is 101325 Pa, this is equivalent to approximately ______ kPa.
Match each term with its appropriate unit:
Match each term with its appropriate unit:
Which scenario best illustrates Pascal's Principle?
Which scenario best illustrates Pascal's Principle?
The shape of a container affects the pressure at a given depth in a stationary fluid.
The shape of a container affects the pressure at a given depth in a stationary fluid.
Explain how the use of a smaller piston to generate pressure can lift a heavier load in a hydraulic system.
Explain how the use of a smaller piston to generate pressure can lift a heavier load in a hydraulic system.
The formula for the pressure difference between two points in a fluid at rest is $\Delta P = -\rho g (y_2 - y_1)$, where $y_2 - y_1$ represents the ______ between the two points.
The formula for the pressure difference between two points in a fluid at rest is $\Delta P = -\rho g (y_2 - y_1)$, where $y_2 - y_1$ represents the ______ between the two points.
Match the pressure measuring device with the type of pressure it primarily measures:
Match the pressure measuring device with the type of pressure it primarily measures:
In the context of fluid pressure, what does 'hydrostatic' refer to?
In the context of fluid pressure, what does 'hydrostatic' refer to?
The pressure in the human eye (aqueous humor) is typically higher than atmospheric pressure.
The pressure in the human eye (aqueous humor) is typically higher than atmospheric pressure.
Explain the principle behind measuring blood pressure using a sphygmomanometer.
Explain the principle behind measuring blood pressure using a sphygmomanometer.
In the equation $P = P_{atm} + P_g$, $P_g$ represents the ______.
In the equation $P = P_{atm} + P_g$, $P_g$ represents the ______.
Match the unit of pressure with its abbreviation:
Match the unit of pressure with its abbreviation:
Which of the following factors does NOT affect the pressure exerted by a fluid at a certain depth?
Which of the following factors does NOT affect the pressure exerted by a fluid at a certain depth?
Gauge pressure can be negative.
Gauge pressure can be negative.
Explain why the height of the liquid column in a barometer is independent of the diameter of the tube.
Explain why the height of the liquid column in a barometer is independent of the diameter of the tube.
If the gauge pressure is zero, then the absolute pressure is equal to ______.
If the gauge pressure is zero, then the absolute pressure is equal to ______.
Match the application with the pressure principle it utilizes:
Match the application with the pressure principle it utilizes:
Which best explains why objects at the bottom of the ocean experience immense pressure?
Which best explains why objects at the bottom of the ocean experience immense pressure?
In a fluid, pressure always acts parallel to the surface it contacts.
In a fluid, pressure always acts parallel to the surface it contacts.
Compare and contrast the use of mercury and water in barometers. Why is mercury typically preferred?
Compare and contrast the use of mercury and water in barometers. Why is mercury typically preferred?
If the atmospheric pressure is 1 atm and the gauge pressure of a tire is 30 psi, the absolute pressure in the tire is approximately ______ atm. (Note: 1 atm ≈ 14.7 psi)
If the atmospheric pressure is 1 atm and the gauge pressure of a tire is 30 psi, the absolute pressure in the tire is approximately ______ atm. (Note: 1 atm ≈ 14.7 psi)
Match each type of pressure with its reference point:
Match each type of pressure with its reference point:
Flashcards
Pressure
Pressure
Force exerted by a fluid per unit area; a special type of stress.
Fluid
Fluid
A substance that can flow and conform to the shape of its container.
Density
Density
Mass per unit volume of a substance.
Direction of Fluid Pressure
Direction of Fluid Pressure
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Pascal's Principle
Pascal's Principle
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Pressure and Depth
Pressure and Depth
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Absolute Pressure
Absolute Pressure
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Gauge Pressure
Gauge Pressure
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Open Tube Manometer
Open Tube Manometer
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Mercury Barometer
Mercury Barometer
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Bourdon Gauge
Bourdon Gauge
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Electronic Transducers
Electronic Transducers
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Sphygmomanometer
Sphygmomanometer
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Study Notes
Liquid and Gases & Pressure
- Pressure is a special type of stress that applies to liquids and gases.
- Fluids includes air, water, blood etc.
- Learning goals include understanding what is a fluid, density, properties of pressure in a fluid, measurement of pressure, gauge pressure and absolute pressure, and pressure in the body and its measurement.
Properties of Pressure
- Fluids exert pressure in all directions.
- At a given depth, pressure is equal in all directions within a fluid.
- Fluid pressure always acts perpendicular to the surface in contact.
- Pressure applied to an enclosed fluid is transmitted undiminished to all parts, known as Pascal’s Principle.
- Pressure can produce a change in volume.
- The pressure is the same at equal depths in a stationary fluid with uniform density, regardless of the container shape.
Pascal's Principle
- Pressure applied to an enclosed fluid is transmitted equally to all parts of the fluid.
Pressure Formula
- For a fluid with constant density (represented by ȡ), the difference in pressure (ΔP) between two heights (y1 and y2) is given by: ΔP = P2 - P1 = -pg(y2 - y1).
- Where:
- ȡ is density in kg/m³.
- g is the acceleration due to gravity in kg m/s².
- P1 is the pressure at point 1 in Pascals (Pa).
- P2 is the pressure at point 2 in Pascals (Pa).
- If point 1 is at depth h, and point 2 is on the surface of the fluid then: P2=Psuf = Patm = atmospheric pressure, and P1 = P
- Then rearranged: P = Psuf + pgh = Patm + pgh.
Absolute and Gauge Pressure
- Absolute pressure is relative to a vacuum.
- Gauge pressure is differential to atmospheric pressure.
- Formula: P = Patm + Pg (absolute pressure), or Pg = P - Patm (gauge pressure).
Open Tube Manometer
- It measures gauge pressure, which equals to the difference between the unknown pressure and the atmospheric pressure.
- It's set up involves a U-tube containing a liquid, one side connected to a vessel with unknown pressure (P), and the other open to atmospheric pressure (Patm).
- Pressure at equal depth in a stationary fluid is uniform.
- P + pgyB = Patm + pgyA, therefore P - Patm = pg(yA - yB) = -pgh.
Pressure Measurement Instruments
- Mercury Barometer
- Measures atmospheric pressure directly.
- P= Patm + 0 Pa.
- Bourdon Gauge
- Flexible tube closed at one end.
- Pressure applied at the other end straightens the tube.
- It moves a pointer across a scale to indicate pressure.
- Electronic Transducers
- Pressure bends the transducer face.
- Strain changes resistance of fine wires bonded on the surface.
- Applications include medical, aircraft, automotive, and industrial safety.
Typical Fluid Pressures in Humans
- Maximum arterial blood pressure: 14,000 to 19,000 Pa
- Brain (lying down): 700 to 1,600 Pa
- Eye (aqueous humour): 1,600 to 3,200 Pa
- Gastrointestinal: 1,300 to 2,700 Pa
- Intrathoracic: -500 to -1,000 Pa
- Middle ear: < 130 Pa
- Bladder (during micturition): 14,700 Pa
Sphygmomanometer
- It measures blood pressures because pressures are often quoted as heights of mercury (mmHg)
Pressure Units
- SI unit: Pascal (Pa), where 1 Pa=1Nm−2
- 1 atm = 1.013 × 105 Pa
- 1 atm = 1.013 bar
- 1 atm = 1.013 × 103 mbar
- 1 mbar = 102 Pa
- 1 atm = 760 mm Hg
- 1 atm = 29.5 inches Hg
- 1 bar = 105 Pa = 0.9872 atm
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