Question 1

What is the physical process whereby the gaseous form of a substance is changed back into its liquid state?

Accepted Answer

During condensation, a gas turns back into a liquid.

Question 2

Which of the following is false about evaporation?

Accepted Answer

Vaporization is the change of state from liquid to gas. Vaporization requires heat energy. According to the first law of thermodynamics, this heat energy must come from the surroundings. In one form of vaporization, called evaporation, heat is taken from the air surrounding the liquid, thereby cooling the air.

Question 3

Which of the following statements correctly describe gases?
1) Gases exhibit the phenomenon of flow.
2) Molecular forces of attraction are minimal.
3) Gases are difficult to compress.
4) Gases expand to fill their container.

Accepted Answer

1) Gases exhibit the phenomenon of flow, which means they can move from one place to another.
2) Molecular forces of attraction are minimal, and the molecules move freely in all directions.
4) Gases expand to fill their container as the molecules can move to fill the available space. 
However, gases can be compressed with the application of pressure, so statement 3 is incorrect.

Question 4

A near-drowning patient has a recorded body temperature of 30° C. What is the equivalent temperature in degrees Fahrenheit?

Accepted Answer

To convert degrees Celsius to degrees Fahrenheit, simply reverse the formula given in question 4: ° F = (9/5 F1F1F1S1F1F1F10 ° C) + 32.

Question 5

Archimedes' principle is applied clinically in which of the following devices?

Accepted Answer

Clinically, Archimedes' principle is used to measure the specific gravity of certain liquids. A hydrometer is used to measure the specific gravity of certain liquids.

Question 6

What is the primary means by which heat transfer occurs in fluids?

Accepted Answer

Heat transfer in both liquids and gases occurs mainly by convection.

Question 7

At what temperature do all kinetic activities of matter cease?

Accepted Answer

The SI (Systeme Internationale) units for temperature are degrees Kelvin, with a zero point equal to absolute zero (0 K).

Question 8

After placing a liquid into a small-diameter glass tube, you observe the formation of a convex (upwardly curved) meniscus. What conclusion is correct?

Accepted Answer

When the liquid is water, the meniscus is concave because the water molecules at the surface adhere to the glass more strongly than they cohere to each other. In contrast, a mercury meniscus is convex. In this case, the cohesive forces pulling together the mercury atoms exceed the adhesive forces trying to attract the mercury to the glass.

Question 9

What is the internal force that opposes the flow of fluids (equivalent to friction between solid substances)?

Accepted Answer

Viscosity is the force opposing a fluid's flow.

Question 10

Which of the following is a good clinical example of using the principle of convection to transfer heat?

Accepted Answer

This is the principle behind forced-air heating in houses and convection heating in infant incubators.

Question 11

Which of the following would be the worst heat conductor?

Accepted Answer

With fewer molecular collisions than in solids and liquids, gases exhibit low thermal conductivity.

Question 12

By which of the following means can the internal energy of a substance be increased?
1) Cooling the substance
2) Performing work on the substance
3) Heating the substance

Accepted Answer

The internal energy of a substance can be increased by performing work on the substance (2) and by heating the substance (3). Cooling the substance would decrease its internal energy, not increase it.

Question 13

What term is used for the transfer of heat by the direct interaction of atoms or molecules in a hot area with atoms or molecules in a cooler area?

Accepted Answer

Conduction is the transfer of heat by direct contact between hot and cold molecules.

Question 14

Which of the following equations can be used to calculate the pressure exerted by a liquid?

Accepted Answer

The pressure exerted by a liquid depends on both its height (depth) and weight density (weight per unit volume), which is shown in equation form:

Question 15

Which of the following are true of liquids?
1) They are easy to compress.
2) They exert pressure.
3) They exert buoyant force.
4) They conform to their containers.

Accepted Answer

1) Liquids are difficult to compress because they have very little space between their particles.
2) Liquids exert pressure because their molecules are constantly colliding with the walls of the container they are in.
3) Liquids exert buoyant force because they are less dense than some solids, allowing them to float.
4) Liquids conform to their containers because they take on the shape of the container they are placed in due to the weak attraction between their particles.

Question 16

Which of the following would help to decrease a patient's loss of body heat?
1) Increase the temperature of the room.
2) Increase the exposed skin surface area.
3) Move the patient away from cold windows.

Accepted Answer

Increasing the temperature of the room and moving the patient away from cold windows can both help to decrease the patient's loss of body heat. However, increasing the exposed skin surface area would actually increase the patient's loss of body heat, so option 2 should be eliminated. Therefore, the best choice is 1 and 3 only, or option D.

Question 17

Which of the following is false about viscosity?

Accepted Answer

Laminar flow consists of concentric layers of fluid flowing parallel to the tube wall at velocities that increase toward the center.

Question 18

A patient has a recorded body temperature of 106° F. What is this temperature in degrees Celsius?

Accepted Answer

To convert degrees Fahrenheit to degrees Celsius, use the following formula: ° C = 5/9 F1F1F1S1F1F1F10 (° F - 32).

Question 19

According to Pascal's principle, the pressure exerted by a liquid in a container depends on which of the following?
1) Depth of the liquid
2) Density of the liquid
3) Shape of the container

Accepted Answer

Pascal's principle states that the pressure exerted by a liquid in a container is transmitted equally in all directions and depends only on the depth of the liquid and the density of the liquid. The shape of the container does not affect the pressure. Therefore, the correct choices are 1 and 2, but not 3.

Question 20

Which of the following methods of heat transfer requires no direct contact between the warmer and cooler substances?

Accepted Answer

While conduction and convection require direct contact between two substances, radiant heat transfer occurs without direct physical contact.

Quiz 6: Physical Principles of Respiratory Care