Physics Units and Concepts Quiz

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Questions and Answers

What is the formula used to calculate force?

F = mass (m) + acceleration (a)

F = mass (m) / acceleration (a)

F = mass (m) x acceleration (a) (correct)

F = mass (m) - acceleration (a)

Which unit is used to measure pressure?

Pascals (Pa) (correct)

Grams (g)

Joules (J)

Newtons (N)

What happens according to Newton's 3rd Law of Reciprocal Action?

For every force, there is an equal force exerted.

For every action, there is a greater reaction.

For every motion, there is a corresponding energy.

For every action, there is a opposite equal reaction. (correct)

Which type of energy is defined as the capacity to do work?

Potential Energy Signup and view all the answers

How is work defined in physical terms?

Force x Distance Signup and view all the answers

What factor affects gauge pressure?

Difference between absolute pressure and atmospheric pressure Signup and view all the answers

Which unit measures energy?

Joules (J) Signup and view all the answers

What do Kinetic Energy and Work have in common?

Both are the same concept Signup and view all the answers

Which component of a laser determines the directionality of the laser beam?

Brewster angle Signup and view all the answers

Which type of laser has a longer wavelength and is commonly used in ENT surgeries?

Carbon dioxide laser Signup and view all the answers

What property of laser beams makes distance from the source have negligible safety effects?

They do not decay Signup and view all the answers

Which wavelength is associated with the neodymium-YAG laser, making it penetrate deeper than water?

1 K wavelength Signup and view all the answers

Which intervention is crucial for OR staff when lasers are not in use?

Engage laser in standby mode Signup and view all the answers

What type of safety equipment is recommended for all personnel working with lasers?

Laser safety goggles Signup and view all the answers

Which anesthesia intervention is necessary for patients when lasers are used in the operating room?

EtO2 and laser safety goggles Signup and view all the answers

What characteristic of the neodymium-YAG laser complicates postoperative healing?

Delayed postoperative swelling Signup and view all the answers

What is a key fire risk associated with the use of lasers in surgery?

Presence of flammable materials Signup and view all the answers

What factor contributes to the energy levels associated with longer wavelengths in lasers?

Decreased frequency Signup and view all the answers

What happens to the velocity of a fluid as it passes through a narrowing in a tube according to Bernoulli's Principle?

It increases with a corresponding decrease in pressure. Signup and view all the answers

Which type of flow is characterized by smooth and regular movement of fluid with predictable behavior?

Laminar flow Signup and view all the answers

What effect does viscosity have on fluid flow according to Poiseuille's Law?

Flow is indirectly proportional to viscosity. Signup and view all the answers

What is the significance of Reynolds Number in fluid dynamics?

It predicts whether flow will be laminar or turbulent. Signup and view all the answers

What occurs in turbulent flow?

Irregular swirls and eddies are present. Signup and view all the answers

According to Venturi Effect, what occurs when fluid enters a narrowing space?

Extra air is pulled in due to a drop in pressure. Signup and view all the answers

Which factor contributes to increased resistance in turbulent flow?

Irregular surfaces and high velocities. Signup and view all the answers

Which factor is NOT directly proportional to Reynolds Number?

Viscosity Signup and view all the answers

What type of flow occurs at lower fluid velocities and results in predictable flow patterns?

Laminar flow Signup and view all the answers

How does the pressure gradient affect fluid flow according to Poiseuille's Law?

Flow is directly proportional to pressure gradient. Signup and view all the answers

Which method of O2 analysis uses a semipermeable membrane to measure electrical potential?

Electro-Galvanic Cell Signup and view all the answers

What is the primary principle behind the Severinghaus PCO2 electrode?

CO2 reacts to produce carbonic acid that alters pH. Signup and view all the answers

Which gas analysis method requires a magnetic field to deflect ionized molecules?

Mass Spectrometry Signup and view all the answers

What limitation does infrared analysis have when measuring gases?

It cannot measure oxygen, nitrogen, or helium. Signup and view all the answers

What aspect of the Beer-Lambert Law affects the absorption of electromagnetic waves?

Thickness and absorbing properties Signup and view all the answers

In capnography, what does Phase II of the waveform represent?

Exhalation of dead space Signup and view all the answers

Which angle in capnography indicates the transition from a mix of gases to only alveolar air?

Alpha angle Signup and view all the answers

What causes a prolonged expiratory upstroke in capnography?

COPD or asthma bronchospasm Signup and view all the answers

What is a significant drawback of using colorimetric sensors for CO2 detection?

They only detect the presence of CO2, not its concentration. Signup and view all the answers

What fundamental principle does the paramagnetic oxygen analyzer rely on?

Movement of unpaired electrons in oxygen Signup and view all the answers

What defines a normal baseline CO2 level in capnography?

35-40 mmHg Signup and view all the answers

What is the main function of a polarographic electrode in O2 analysis?

It detects partial pressure of O2 through current flow. Signup and view all the answers

Which of the following is a limitation of inferred analysis?

Can misinterpret gas concentrations due to interference. Signup and view all the answers

What is the primary limitation of pulse oximetry at SpO2 values below 70%?

Inaccurate readings become more common Signup and view all the answers

Which of the following is an advantage of pulse oximetry?

Provides continuous monitoring Signup and view all the answers

What do the light-emitting diodes in a pulse oximeter emit?

Red and near-infrared light Signup and view all the answers

Which statement accurately describes the Beer-Lambert Law as applied in anesthesia?

It compares light transmission before and after passing through a medium Signup and view all the answers

What constitutes the primary sample in cerebral oximetry measurements?

75% venous and 25% arterial blood Signup and view all the answers

What is a common source of error in pulse oximetry readings?

Motion artifacts Signup and view all the answers

In the context of pulse oximetry, what does carboxyhemoglobin cause?

False high readings of SpO2 Signup and view all the answers

Which of the following describes a disadvantage of cerebral oximetry?

Unpredictability in readings due to sample composition Signup and view all the answers

Which of the following factors can negatively impact pulse oximetry accuracy?

Deep skin pigmentation Signup and view all the answers

What is a principle drawback of the Beer-Lambert Law in cerebral oximetry?

It must be modified to suit different conditions Signup and view all the answers

Study Notes

Units of Measurement

Mass is measured in grams (g).
Length is measured in meters (m).
Volume is measured in liters (L).
Time is measured in seconds (sec).

Force

Force is defined as the amount of energy required to change an object's state of rest to motion.
Force is calculated using the formula: F = mass (m) x acceleration (a).
Force is measured in Newtons.
One Newton is the energy needed to move 1 kg of mass 1 meter.
Gravity is a force: a force of attraction between masses.
Larger molecules attract other molecules through gravity.
Hydrostatic pressure is affected by gravity and distance from the heart.

Pressure

Pressure is defined as the amount of force applied per unit area.
Pressure is measured in Pascals (Pa) and Kilopascals (kPa).
Bourdon Gauge: directly measures pressure, used on compressed gas cylinders.
Absolute pressure = atmospheric pressure + gauge pressure.
Gauge pressure = absolute pressure - atmospheric pressure.

Energy

Energy is measured in Joules.
Potential energy (PE): stored energy that can be converted to work.
Kinetic energy (KE): the exertion of force.
PE and KE exist in equilibrium.
KE and Work are essentially the same.
Law of Conservation of Energy: energy cannot be destroyed or created, only transferred or converted.

Work

Work is calculated as Force x Distance.
KE and Work are essentially the same.

Laplace's Law

Laplace's Law describes the relationship between the pressure of a fluid inside a closed container, the radius of the container, and the tension of the container's wall.
Cylinders: the pressure inside a cylinder is inversely proportional to the radius of the cylinder.
Spheres: the pressure inside a sphere is inversely proportional to the radius of the sphere.

Pascal's Principle

Pascal's Principle states that the pressure applied to an enclosed fluid is transmitted equally to every point within the fluid.

Surface Tension

Surface Tension is the force that exists at the interface between a liquid and a gas.
Surface Tension is influenced by the cohesive forces between liquid molecules, adhesion forces between the liquid and another surface, and the temperature.

Venturi Effect

The Venturi Effect describes the decrease in pressure that occurs when a fluid flows through a narrowing space, resulting in an increase in velocity.

Fluid Mechanics

Fluids are susceptible to pressure and gravity.
Fluids include liquids and gases.
Fluid dynamics are defined by the response to stress.
Perpendicular stress is resistance to compression.
Liquids resist compression while gases are compressible and expandable.
Tangential stress: resistance to flow due to surface interaction.
Friction is proportional to viscosity.
Viscosity is the inherent property of a fluid that resists flow.

Types of Flow

Laminar flow: predictable, with less tangential stress at the center of the flow and more stress on the bottom and outside.
Transitional flow: most common type of flow in the body.
Turbulent flow: irregular, swirling flow that occurs at high velocities, sharp bends, angles, and irregularities.

Poiseuille's Law

Poiseuille's Law predicts the rate of flow through a pipe.
Flow is exponentially proportional to the radius of the pipe.
Flow is directly proportional to the pressure gradient.
Flow is inversely proportional to viscosity.
Flow is inversely proportional to the length of the pipe.

Reynold's Number

Index that combines Poiseuille's Law and fluid density to determine whether a given flow will be laminar or turbulent.
Flow is directly proportional to velocity, diameter, and density.
Flow is inversely proportional to viscosity.
Laminar flow: Reynold's number < 2000.

Bernoulli's Principle

As fluid flows through a constriction, velocity increases and pressure decreases.
Velocities and pressures exist in an inverse relationship, Velocity takes away KE from pressure (Law of Conservation).

Gas Analysis

Oxygen (O2) Analysis
- Electro-Galvanic Cell (Fuel Cells): Oxygen passes through a semipermeable membrane and dissolves into an electrolyte solution, generating electrical potential measured by a voltmeter.
- Polarographic Electrode (Clark Electrode): Applied voltage causes oxygen to reduce at the cathode, creating a current proportional to O2 partial pressure.
- Paramagnetic Oxygen Analyzer: Oxygen's paramagnetic properties are used to measure its concentration by analyzing pressure differences caused by rapidly alternating electromagnetic fields.
- Fluorescence-Quenching: Oxygen absorbs photons, preventing emitted light, allowing concentration analysis through the amount of emitted photons.
Carbon Dioxide (CO2) Analysis
- Severinghaus PCO2 electrode: CO2 diffuses into a bicarbonate solution and reacts with water producing carbonic acid, measured by a voltmeter.
- Colorimetric Sensor: CO2 dissolves into a solution, altering pH and activating a pH-sensitive dye, creating a color change which can be measured.
Other Gas Analysis
- Mass Spectrometry: Ionized gas molecules are deflected by a magnetic field, creating electrical currents measured at collectors.
- Infrared analysis: Gases absorb infrared radiation at distinct wavelengths, allowing measurement by analyzing changes in the infrared beam.
- Raman Scattering Analysis: analyzes scattered light from molecules hit by a laser beam.

Beer-Lambert Law

The Beer-Lambert Law describes the relationship between the absorption of electromagnetic radiation and the concentration of the absorbing substance.
Absorption is determined by the thickness and absorbing properties of the substance.

Capnography

Capnography is a tool that measures the concentration of carbon dioxide (CO2) in exhaled air.
Capnographs use a specific waveform to display the amount of CO2 in exhaled tidal volume over time.
Phases of Capnography Waveform:
- Phase 0: Inspiratory phase.
- Phase 1: Exhalation of dead space, minimal to no CO2.
- Phase II: Exhalation of mixed alveolar and dead space gas, expired CO2 from the upper airways.
- Phase III: Alveolar plateau, represents alveolar pCO2.
- Phase IV: End-tidal CO2, measured at this point.
Angles of Capnography Waveform:
- Alpha Angle: between phases II and III, represents transition to just alveolar air exhalation.
- Beta Angle: between phases III and IV, represents transition to inspiration.

Pulse Oximetry

Pulse oximetry is a non-invasive tool that measures the percentage of hemoglobin in the blood that is saturated with oxygen (SpO2).
Pulse oximeter probe emits red and infrared light, which is absorbed differently by oxyhemoglobin and deoxyhemoglobin, allowing for SpO2 calculation.
Advantages:
- Non-invasive.
- Easy to apply.
- Continuous monitoring.
- Earlier detection of desaturation.
- Inexpensive.
Disadvantages:
- Prone to artifact.
- Delayed measurements (30-60 seconds).
- Inaccurate at SpO2 values below 70%.
- Rare risk of burns in poor perfusion states.
Inaccuracies:
- Falsely high readings: carbon monoxide poisoning, methemoglobinemia.
- Underestimated readings: dyes such as methylene blue.
- Other sources of error: ambient light, skin pigmentation, electrosurgery, motion artifact, nail polish.

Cerebral Oximetry

Cerebral oximetry measures the oxygen saturation of the blood in the brain.
It relies on the scattering and reflection of radiation, which is highly unpredictable and influenced by venous and arterial blood.
The Beer-Lambert Law does not apply directly, so modified equations are used.

Lasers

Lasers are high-energy light beams that are concentrated and directional.
Components of a laser:
- Energy source (example: electricity)
- Brewster Angle- mirrors that determine directionality.
- Resonant chamber: contains the laser medium where the laser light amplifies.
- Electrodes (anode and cathode).
Lasers are classified based on their wavelengths which correspond to their energy levels.
Risks and Dangers:
- Protective eyewear is crucial for all personnel.
- Reflected radiation is as hazardous as direct radiation.
- Laser beams do not decay with distance: distance from the source has minimal safety effects.
Types of Lasers:
- Carbon Dioxide Laser: superficial penetration, used for ENT surgeries and some neurosurgeries, infrared wavelength, not fiberoptic compatible.
- Nd-YAG laser: deeper penetration, wavelengths are better absorbed by water, used for distal airway surgeries, good coagulation, can cause delayed swelling.
Anesthesia Considerations:
- Laser in standby mode when not in use.
- Secondary light beams for aiming assistance.
- Monitor the location of instruments and flammable materials.
- Laser safety goggles for all personnel.
- Clear communication and a planned approach for crisis response.
- Patient should wear laser safety goggles.
- Monitor EtO2 (end-tidal oxygen) levels.

Fire Risks & Emergency Precautions

Use laser safety goggles for all staff members.
Minimize flammable materials in the room where a laser is in use.
Have a plan for emergency response to fires.
Be prepared to extinguish a fire with appropriate equipment and resources.

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Description

Test your understanding of fundamental physics concepts such as units of measurement, force, and pressure. This quiz covers essential definitions, formulas, and measurement units associated with these topics. Perfect for students looking to reinforce their knowledge in physics.