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Thermodynamics: An Engineering Approach

Yunus A. Çengel, Michael A. Boles

Chapter 1

Introduction and Basic Concepts - all with Video Answers

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Chapter Questions

00:35

Problem 1

What is the difference between the classical and the statistical approaches to thermodynamics?

Mayukh Banik
Mayukh Banik
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00:24

Problem 2

Why does a bicyclist pick up speed on a downhill road even when he is not pedaling? Does this violate the conservation of energy principle?

Mayukh Banik
Mayukh Banik
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00:55

Problem 3

One of the most amusing things a person can experience is when a car in neutral appears to go uphill when its brakes are released. Can this really happen or is it an optical illusion? How can you verify if a road is pitched uphill or downhill?

Mayukh Banik
Mayukh Banik
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00:16

Problem 4

An office worker claims that a cup of cold coffee on his table warmed up to $80^{\circ} \mathrm{C}$ by picking up energy from the surrounding air, which is at $25^{\circ} \mathrm{C}$. Is there any truth to his claim? Does this process violate any thermodynamic laws?

Mayukh Banik
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00:42

Problem 5

What is the difference between kg-mass and kg force?

Mayukh Banik
Mayukh Banik
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00:27

Problem 6

Explain why the light-year has the dimension of length.

Mayukh Banik
Mayukh Banik
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00:15

Problem 7

What is the net force acting on a car cruising at a constant velocity of $70 \mathrm{km} / \mathrm{h}(a)$ on a level road and $(b)$ on an uphill road?

Mayukh Banik
Mayukh Banik
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01:17

Problem 8

At $45^{\circ}$ latitude, the gravitational acceleration as a function of elevation $z$ above sea level is given by $g=a-b z$ where $a=9.807 \mathrm{m} / \mathrm{s}^{2}$ and $b=3.32 \times 10^{-6} \mathrm{s}^{-2}$. Determine
the height above sea level where the weight of an object will decrease by 0.3 percent.

Mayukh Banik
Mayukh Banik
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00:15

Problem 9

What is the weight, in $\mathrm{N}$, of an object with a mass of $200 \mathrm{kg}$ at a location where $g=9.6 \mathrm{m} / \mathrm{s}^{2} ?$

Mayukh Banik
Mayukh Banik
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00:51

Problem 10

A 3 -kg plastic tank that has a volume of $0.2 \mathrm{m}^{3}$ is filled with liquid water. Assuming the density of water is $1000 \mathrm{kg} / \mathrm{m}^{3},$ determine the weight of the combined system.

Mayukh Banik
Mayukh Banik
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02:24

Problem 11

The constant-pressure specific heat of air at $25^{\circ} \mathrm{C}$ is $1.005 \mathrm{kJ} / \mathrm{kg} \cdot^{\circ} \mathrm{C} .$ Express this value in $\mathrm{kJ} / \mathrm{kg} \cdot \mathrm{K}, \mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C}, \mathrm{kcal} /$ $\mathrm{kg} \cdot^{\circ} \mathrm{C},$ and $\mathrm{Btu} / \mathrm{lbm} \cdot^{\circ} \mathrm{F}$.

Mayukh Banik
Mayukh Banik
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01:13

Problem 12

A 3 -kg rock is thrown upward with a force of $200 \mathrm{N}$ at a location where the local gravitational acceleration is $9.79 \mathrm{m} / \mathrm{s}^{2}$. Determine the acceleration of the rock, in $\mathrm{m} / \mathrm{s}^{2}$.

Mayukh Banik
Mayukh Banik
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01:29

Problem 13

Solve Prob. $1-12$ using EES (or other) software. Print out the entire solution, including the numerical results with proper units.

Hariprasad Annamalai
Hariprasad Annamalai
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00:54

Problem 14

A 4-kW resistance heater in a water heater runs for 3 hours to raise the water temperature to the desired level. Determine the amount of electric energy used in both kWh and kJ.

Mayukh Banik
Mayukh Banik
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01:01

Problem 15

A $150-l b m$ astronaut took his bathroom scale (a spring scale and a beam scale (compares masses) to the moon where the local gravity is $g=5.48 \mathrm{ft} / \mathrm{s}^{2} .$ Determine how much he will weigh $(a)$ on the spring scale and $(b)$ on the beam scale.

Mayukh Banik
Mayukh Banik
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00:32

Problem 16

The gas tank of a car is filled with a nozzle that discharges gasoline at a constant flow rate. Based on unit considerations of quantities, obtain a relation for the filling time in terms of the volume $V$ of the $\operatorname{tank}(\text { in } \mathrm{L})$ and the discharge rate of gasoline $V(\text { in } \mathrm{L} / \mathrm{s})$

Mayukh Banik
Mayukh Banik
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01:07

Problem 17

A pool of volume $V$ (in $\mathrm{m}^{3}$ ) is to be filled with water using a hose of diameter $D$ (in $\mathrm{m}$ ). If the average discharge velocity is $V(\text { in } \mathrm{m} / \mathrm{s})$ and the filling time is $t(\text { in } \mathrm{s}),$ obtain a relation for the volume of the pool based on considerations of quantities involved.

Mayukh Banik
Mayukh Banik
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00:38

Problem 18

A large fraction of the thermal energy generated in the engine of a car is rejected to the air by the radiator through the circulating water. Should the radiator be analyzed as a closed system or as an open system? Explain.

Mayukh Banik
Mayukh Banik
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00:34

Problem 19

You are trying to understand how a reciprocating air compressor (a piston-cylinder device) works. What system would you use? What type of system is this?

Mayukh Banik
Mayukh Banik
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00:29

Problem 20

A can of soft drink at room temperature is put into the refrigerator so that it will cool. Would you model the can of soft drink as a closed system or as an open system? Explain.

Mayukh Banik
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00:57

Problem 21

What is the difference between intensive and extensive properties?

Mayukh Banik
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00:12

Problem 22

Is the weight of a system an extensive or intensive property?

Mayukh Banik
Mayukh Banik
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00:55

Problem 23

Is the state of the air in an isolated room completely specified by the temperature and the pressure? Explain.

Mayukh Banik
Mayukh Banik
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00:34

Problem 24

The molar specific volume of a system $\bar{v}$ is defined as the ratio of the volume of the system to the number of moles of substance contained in the system. Is this an extensive or intensive property?

Mayukh Banik
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01:06

Problem 25

What is a quasi-equilibrium process? What is its importance in engineering?

Mayukh Banik
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00:29

Problem 26

Define the isothermal, isobaric, and isochoric processes.

Mayukh Banik
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00:30

Problem 27

How would you describe the state of the water in a bathtub? How would you describe the process that this water experiences as it cools?

Mayukh Banik
Mayukh Banik
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00:37

Problem 28

When analyzing the acceleration of gases as they flow through a nozzle, what would you choose as your system? What type of system is this?

Mayukh Banik
Mayukh Banik
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00:23

Problem 29

What is specific gravity? How is it related to density?

Mayukh Banik
Mayukh Banik
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03:17

Problem 30

The density of atmospheric air varies with elevation, decreasing with increasing altitude. $(a)$ Using the data given in the table, obtain a relation for the variation of density with elevation, and calculate the density at an elevation of $7000 \mathrm{m} .(b)$ Calculate the mass of the atmosphere using the correlation you obtained. Assume the earth to be a perfect sphere with a radius of $6377 \mathrm{km},$ and take the thickness of the atmosphere to be $25 \mathrm{km}$

Hariprasad Annamalai
Hariprasad Annamalai
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00:27

Problem 31

What are the ordinary and absolute temperature scales in the SI and the English system?

Mayukh Banik
Mayukh Banik
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00:45

Problem 32

Consider an alcohol and a mercury thermometer that read exactly $0^{\circ} \mathrm{C}$ at the ice point and $100^{\circ} \mathrm{C}$ at the steam point. The distance between the two points is divided into 100 equal parts in both thermometers. Do you think these thermometers will give exactly the same reading at a temperature of, say, $60^{\circ} \mathrm{C} ?$ Explain.

Mayukh Banik
Mayukh Banik
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01:08

Problem 33

Consider two closed systems A and B. System A contains $3000 \mathrm{kJ}$ of thermal energy at $20^{\circ} \mathrm{C},$ whereas system $\mathrm{B}$ contains $200 \mathrm{kJ}$ of thermal energy at $50^{\circ} \mathrm{C}$. Now the systems are brought into contact with each other. Determine the direction of any heat transfer between the two systems.

Keshav Singh
Keshav Singh
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00:29

Problem 34

The deep body temperature of a healthy person is $37^{\circ} \mathrm{C} .$ What is it in kelvins?

Mayukh Banik
Mayukh Banik
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00:37

Problem 35

What is the temperature of the heated air at $150^{\circ} \mathrm{C}$ in $^{\circ} \mathrm{F}$ and $\mathrm{R} ?$

Mayukh Banik
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01:04

Problem 36

The temperature of a system rises by $70^{\circ} \mathrm{C}$ during a heating process. Express this rise in temperature in kelvins.

Narayan Hari
Narayan Hari
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00:29

Problem 37

The flash point of an engine oil is $363^{\circ} \mathrm{F}$. What is the absolute flash-point temperature in $\mathrm{K}$ and $\mathrm{R}$ ?

Mayukh Banik
Mayukh Banik
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01:18

Problem 38

The temperature of ambient air in a certain location is measured to be $-40^{\circ} \mathrm{C}$. Express this temperature in Fahrenheit $\left(^{\circ} \mathrm{F}\right),$ Kelvin $(\mathrm{K}),$ and Rankine $(\mathrm{R})$ units.

Mayukh Banik
Mayukh Banik
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00:33

Problem 39

The temperature of a system drops by $45^{\circ} \mathrm{F}$ during a cooling process. Express this drop in temperature in $\mathrm{K}, \mathrm{R}$ and $^{\circ} \mathrm{C}$

Mayukh Banik
Mayukh Banik
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00:59

Problem 40

Explain why some people experience nose bleeding and some others experience shortness of breath at high elevations.

Mayukh Banik
Mayukh Banik
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00:34

Problem 41

A health magazine reported that physicians measured 100 adults' blood pressure using two different arm positions: parallel to the body (along the side) and perpendicular to the body (straight out). Readings in the parallel position were up to 10 percent higher than those in the perpendicular position, regardless of whether the patient was standing, sitting, or lying down. Explain the possible cause for the difference.

Mayukh Banik
Mayukh Banik
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00:17

Problem 42

Someone claims that the absolute pressure in a liquid of constant density doubles when the depth is doubled. Do you agree? Explain.

Mayukh Banik
Mayukh Banik
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00:30

Problem 43

Express Pascal's law, and give a real-world example of it.

Mayukh Banik
Mayukh Banik
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00:54

Problem 44

Consider two identical fans, one at sea level and the other on top of a high mountain, running at identical speeds. How would you compare $(a)$ the volume flow rates and (b) the mass flow rates of these two fans?

Mayukh Banik
Mayukh Banik
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00:25

Problem 45

A vacuum gage connected to a chamber reads $35 \mathrm{kPa}$ at a location where the atmospheric pressure is 92 kPa. Determine the absolute pressure in the chamber.

Mayukh Banik
Mayukh Banik
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01:36

Problem 46

The pressure in a compressed air storage tank is $1200 \mathrm{kPa} .$ What is the tank's pressure in $(a) \mathrm{kN}$ and $\mathrm{m}$ units; (b) $\mathrm{kg}, \mathrm{m},$ and s units; and $(c) \mathrm{kg}, \mathrm{km},$ and s units?

Mayukh Banik
Mayukh Banik
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00:30

Problem 47

The pressure in a water line is 1500 kPa. What is the line pressure in $(a) \mathrm{lb} / \mathrm{ft}^{2}$ units and $(b) \mathrm{lbf} / \mathrm{in}^{2}(\mathrm{psi})$ units?

Mayukh Banik
Mayukh Banik
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00:35

Problem 48

If the pressure inside a rubber balloon is $1500 \mathrm{mmHg},$ what is this pressure in pounds-force per square inch (psi)?

Mayukh Banik
Mayukh Banik
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02:30

Problem 49

A manometer is used to measure the air pressure in a tank. The fluid used has a specific gravity of $1.25,$ and the differential height between the two arms of the manometer is 28 in. If the local atmospheric pressure is 12.7 psia, determine the absolute pressure in the tank for the cases of the manometer arm with the ( $a$ ) higher and ( $b$ ) lower fluid level being attached to the tank.

Hariprasad Annamalai
Hariprasad Annamalai
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01:47

Problem 50

The water in a tank is pressurized by air, and the pressure is measured by a multifluid manometer as shown in Fig. P1-50. Determine the gage pressure of air in the tank if $h_{1}=0.2 \mathrm{m}, h_{2}=0.3 \mathrm{m},$ and $h_{3}=0.4 \mathrm{m} .$ Take the densities of water, oil, and mercury to be $1000 \mathrm{kg} / \mathrm{m}^{3}, 850 \mathrm{kg} / \mathrm{m}^{3},$ and $13,600 \mathrm{kg} / \mathrm{m}^{3},$ respectively.

Hariprasad Annamalai
Hariprasad Annamalai
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00:38

Problem 51

Determine the atmospheric pressure at a location where the barometric reading is $750 \mathrm{mmHg}$. Take the density of mercury to be $13,600 \mathrm{kg} / \mathrm{m}^{3}$

Mayukh Banik
Mayukh Banik
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00:51

Problem 52

A 200-pound man has a total foot imprint area of 72 in $^{2} .$ Determine the pressure this man exerts on the ground if $(a)$ he stands on both feet and $(b)$ he stands on one foot.

Mayukh Banik
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00:34

Problem 53

The gage pressure in a liquid at a depth of $3 \mathrm{m}$ is read to be $42 \mathrm{kPa}$. Determine the gage pressure in the same liquid at a depth of $9 \mathrm{m}$

Mayukh Banik
Mayukh Banik
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01:20

Problem 54

The absolute pressure in water at a depth of $9 \mathrm{m}$ is read to be 185 kPa. Determine $(a)$ the local atmospheric pressure, and $(b)$ the absolute pressure at a depth of $5 \mathrm{m}$ in a liquid whose specific gravity is 0.85 at the same location.

Nick Johnson
Nick Johnson
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01:05

Problem 55

Determine the pressure exerted on the surface of a submarine cruising $175 \mathrm{ft}$ below the free surface of the sea. Assume that the barometric pressure is 14.7 psia and the specific gravity of seawater is 1.03

Mayukh Banik
Mayukh Banik
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00:26

Problem 56

Consider a $70-\mathrm{kg}$ woman who has a total foot imprint area of $400 \mathrm{cm}^{2}$. She wishes to walk on the snow, but the snow cannot withstand pressures greater than 0.5 kPa. Determine the minimum size of the snowshoes needed (imprint area per shoe) to enable her to walk on the snow without sinking.

Mayukh Banik
Mayukh Banik
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01:27

Problem 57

The vacuum pressure of a condenser is given to be 80 kPa. If the atmospheric pressure is $98 \mathrm{kPa}$, what is the gage pressure and absolute pressure in $\mathrm{kPa}, \mathrm{kN} / \mathrm{m}^{2}, \mathrm{lbf} / \mathrm{in}^{2}$
psi, and mmHg.

Mayukh Banik
Mayukh Banik
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00:59

Problem 58

The barometer of a mountain hiker reads 750 mbars at the beginning of a hiking trip and 650 mbars at the end. Neglecting the effect of altitude on local gravitational acceleration, determine the vertical distance climbed. Assume an average air density of $1.20 \mathrm{kg} / \mathrm{m}^{3}$.

Mayukh Banik
Mayukh Banik
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01:55

Problem 59

The basic barometer can be used to measure the height of a building. If the barometric readings at the top and at the bottom of a building are 675 and $695 \mathrm{mmHg}$, respectively, determine the height of the building. Take the densities of air and mercury to be $1.18 \mathrm{kg} / \mathrm{m}^{3}$ and $13,600 \mathrm{kg} / \mathrm{m}^{3}$
respectively.

Mayukh Banik
Mayukh Banik
Numerade Educator
01:17

Problem 60

Solve Prob. $1-59$ using EES (or other) software. Print out the entire solution, including the numerical results with proper units.

Hariprasad Annamalai
Hariprasad Annamalai
Numerade Educator
00:46

Problem 61

The hydraulic lift in a car repair shop has an output diameter of $30 \mathrm{cm}$ and is to lift cars up to $2000 \mathrm{kg}$. Determine the fluid gage pressure that must be maintained in the reservoir.

Mayukh Banik
Mayukh Banik
Numerade Educator
01:59

Problem 62

A gas is contained in a vertical, friction less piston cylinder device. The piston has a mass of $3.2 \mathrm{kg}$ and a cross sectional area of $35 \mathrm{cm}^{2}$. A compressed spring above the piston exerts a force of $150 \mathrm{N}$ on the piston. If the atmospheric pressure is $95 \mathrm{kPa}$, determine the pressure inside the cylinder.

Mayukh Banik
Mayukh Banik
Numerade Educator
02:08

Problem 63

Reconsider Prob. $1-62 .$ Using EES (or other) software, investigate the effect of the spring force in the range of 0 to $500 \mathrm{N}$ on the pressure inside the cylinder. Plot the pressure against the spring force, and discuss the results.

Hariprasad Annamalai
Hariprasad Annamalai
Numerade Educator
01:08

Problem 64

Both a gage and a manometer are attached to a gas tank to measure its pressure. If the reading on the pressure gage is $80 \mathrm{kPa},$ determine the distance between the two fluid levels of the manometer if the fluid is $(a)$ mercury $\left(\rho=13,600 \mathrm{kg} / \mathrm{m}^{3}\right)$ or $(b)$ water $\left(\rho=1000 \mathrm{kg} / \mathrm{m}^{3}\right)$

Mayukh Banik
Mayukh Banik
Numerade Educator
01:15

Problem 65

Reconsider Prob. $1-64 .$ Using EES (or other) software, investigate the effect of the manometer fluid density in the range of 800 to $13,000 \mathrm{kg} / \mathrm{m}^{3}$ on the differential fluid height of the manometer. Plot the differential fluid height against the density, and discuss the results.

Hariprasad Annamalai
Hariprasad Annamalai
Numerade Educator
00:39

Problem 66

A manometer containing oil $\left(\rho=850 \mathrm{kg} / \mathrm{m}^{3}\right)$ is attached to a tank filled with air. If the oil-level difference between the two columns is $80 \mathrm{cm}$ and the atmospheric pressure is $98 \mathrm{kPa}$, determine the absolute pressure of the air in the tank.

Mayukh Banik
Mayukh Banik
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00:28

Problem 67

A mercury manometer $\left(\rho=13,600 \mathrm{kg} / \mathrm{m}^{3}\right)$ is connected to an air duct to measure the pressure inside. The difference in the manometer levels is $15 \mathrm{mm},$ and the atmospheric pressure is 100 kPa. $(a)$ Judging from Fig. $\mathrm{P} 1-67,$ determine if the pressure in the duct is above or below the atmospheric pressure. ( $b$ ) Determine the absolute pressure in the duct.

Mayukh Banik
Mayukh Banik
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00:12

Problem 68

Repeat Prob. 1-67 for a differential mercury height of $45 \mathrm{mm}$.

Mayukh Banik
Mayukh Banik
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03:38

Problem 69

The pressure in a natural gas pipeline is measured by the manometer shown in Fig. $\mathrm{P} 1-69 \mathrm{E}$ with one of the arms open to the atmosphere where the local atmospheric pressure is 14.2 psia. Determine the absolute pressure in the pipeline.

Mayukh Banik
Mayukh Banik
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02:43

Problem 70

Repeat Prob. 1-69E by replacing air by oil with a specific gravity of 0.69.

Mayukh Banik
Mayukh Banik
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02:04

Problem 71

Blood pressure is usually measured by wrapping a closed air-filled jacket equipped with a pressure gage around the upper arm of a person at the level of the heart. Using a mercury manometer and a stethoscope, the systolic pressure (the maximum pressure when the heart is pumping) and the diastolic pressure (the minimum pressure when the heart is resting are measured in mmHg. The systolic and diastolic pressures of a healthy person are about $120 \mathrm{mmHg}$ and $80 \mathrm{mmHg},$ respectively, and are indicated as $120 / 80 .$ Express both of these gage pressures in $\mathrm{kPa},$ psi, and meter water column.

Mayukh Banik
Mayukh Banik
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01:51

Problem 72

The maximum blood pressure in the upper arm of a healthy person is about $120 \mathrm{mmHg}$. If a vertical tube open to the atmosphere is connected to the vein in the arm of the person, determine how high the blood will rise in the tube. Take the density of the blood to be $1050 \mathrm{kg} / \mathrm{m}^{3}$.

Supratim Pal
Supratim Pal
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00:42

Problem 73

Determine the pressure exerted on a diver at $45 \mathrm{m}$ below the free surface of the sea. Assume a barometric pressure of $101 \mathrm{kPa}$ and a specific gravity of 1.03 for seawater.

Mayukh Banik
Mayukh Banik
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04:44

Problem 74

Consider a U-tube whose arms are open to the atmosphere. Now water is poured into the U-tube from one arm, and light oil $\left(\rho=790 \mathrm{kg} / \mathrm{m}^{3}\right)$ from the other. One arm contains 70 -cm-high water, while the other arm contains both fluids with an oil-to-water height ratio of $4 .$ Determine the height of each fluid in that arm.

Mayukh Banik
Mayukh Banik
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02:50

Problem 75

Consider a double-fluid manometer attached to an air pipe shown in Fig. $\mathrm{P} 1-75 .$ If the specific gravity of one fluid is $13.55,$ determine the specific gravity of the other fluid for the indicated absolute pressure of air. Take the atmospheric pressure to be $100 \mathrm{kPa}$.

Mayukh Banik
Mayukh Banik
Numerade Educator
03:03

Problem 76

Freshwater and seawater flowing in parallel horizontal pipelines are connected to each other by a double U-tube manometer, as shown in Fig. $\mathrm{P} 1-76 .$ Determine the pressure difference between the two pipelines. Take the density of seawater at that location to be $\rho=1035 \mathrm{kg} / \mathrm{m}^{3}$. Can the air column be ignored in the analysis?

Mayukh Banik
Mayukh Banik
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01:01

Problem 77

Repeat Prob. 1-76 by replacing the air with oil whose specific gravity is 0.72

Mayukh Banik
Mayukh Banik
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01:15

Problem 78

Calculate the absolute pressure, $P_{1},$ of the manometer shown in Fig. $\mathrm{P} 1-78$ in $\mathrm{kPa}$. The local atmospheric pressure is $758 \mathrm{mmHg}$.

Mayukh Banik
Mayukh Banik
Numerade Educator
00:44

Problem 79

Consider the manometer in Fig. P1-78. If the specific weight of fluid $\mathrm{A}$ is $100 \mathrm{kN} / \mathrm{m}^{3},$ what is the absolute pressure, in $\mathrm{kPa}$, indicated by the manometer when the local atmospheric pressure is $90 \mathrm{kPa} ?$

Mayukh Banik
Mayukh Banik
Numerade Educator
00:42

Problem 80

Consider the manometer in Fig. P1-78. If the specific weight of fluid $\mathrm{B}$ is $20 \mathrm{kN} / \mathrm{m}^{3},$ what is the absolute pressure, in $\mathrm{kPa},$ indicated by the manometer when the local atmospheric pressure is $720 \mathrm{mmHg} ?$

Mayukh Banik
Mayukh Banik
Numerade Educator
05:01

Problem 81

Consider the system shown in Fig. $\mathrm{Pl}-81 .$ If a change of $0.7 \mathrm{kPa}$ in the pressure of air causes the brine-mercury interface in the right column to drop by $5 \mathrm{mm}$ in the brine level in the right column while the pressure in the brine pipe remains constant, determine the ratio of $A_{2} / A_{1}$

Hariprasad Annamalai
Hariprasad Annamalai
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00:56

Problem 82

What is the value of the engineering software packages in $(a)$ engineering education and $(b)$ engineering practice?

Mayukh Banik
Mayukh Banik
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00:40

Problem 83

Determine a positive real root of this equation using EES: $$2 x^{3}-10 x^{0.5}-3 x=-3$$

Mayukh Banik
Mayukh Banik
Numerade Educator
00:51

Problem 84

Solve this system of two equations with two unknowns using EES: $$\begin{aligned}
&x^{3}-y^{2}=7.75\\
&3 x y+y=3.5
\end{aligned}$$

Mayukh Banik
Mayukh Banik
Numerade Educator
00:48

Problem 85

Solve this system of three equations with three unknowns using EES:
$$\begin{array}{c}
x^{2} y-z=1 \\
x-3 y^{0.5}+x z=-2 \\
x+y-z=2
\end{array}$$

Mayukh Banik
Mayukh Banik
Numerade Educator
00:53

Problem 86

Solve this system of three equations with three unknowns using EES:
$$\begin{aligned}
&2 x-y+z=7\\
&\begin{array}{c}
3 x^{2}+3 y=z+3 \\
x y+2 z=4
\end{array}
\end{aligned}$$

Mayukh Banik
Mayukh Banik
Numerade Educator
02:54

Problem 87

Specific heat is defined as the amount of energy needed to increase the temperature of a unit mass of a substance by one degree. The specific heat of water at room temperature is $4.18 \mathrm{kJ} / \mathrm{kg} \cdot^{\circ} \mathrm{C}$ in SI unit system. Using the unit conversion function capability of EES, express the specific heat of water in $(a) \mathrm{kJ} / \mathrm{kg} \cdot \mathrm{K}$ (b) $\mathrm{Btu} / \mathrm{lbm} \cdot^{\circ} \mathrm{F}$ $(c)$ Btu/lbm-R, and (d) \mathrm{kcal} / \mathrm{kg} $^{\circ} \mathrm{C}$ units.

Hariprasad Annamalai
Hariprasad Annamalai
Numerade Educator
01:19

Problem 88

The weight of bodies may change somewhat from one location to another as a result of the variation of the gravitational acceleration $g$ with elevation. Accounting for this variation using the relation in Prob. $1-8,$ determine the weight of an 80 -kg person at sea level $(z=0),$ in Denver $(z=1610 \mathrm{m})$ and on the top of Mount Everest $(z=8848 \mathrm{m})$

Mayukh Banik
Mayukh Banik
Numerade Educator
01:20

Problem 89

A man goes to a traditional market to buy a steak for dinner. He finds a 12 -oz steak $(1 \mathrm{lbm}=16 \mathrm{oz})$ for $\$ 5.50$ He then goes to the adjacent international market and finds a $300-\mathrm{g}$ steak of identical quality for $\$ 5.20 .$ Which steak is the better buy?

Mayukh Banik
Mayukh Banik
Numerade Educator
02:03

Problem 90

What is the weight of a 1 -kg substance in $\mathrm{N}, \mathrm{kN}$ $\mathrm{kg} \cdot \mathrm{m} / \mathrm{s}^{2}, \mathrm{kgf}, \mathrm{lbm} \cdot \mathrm{ft} / \mathrm{s}^{2},$ and lbf?

Mayukh Banik
Mayukh Banik
Numerade Educator
01:57

Problem 91

A hydraulic lift is to be used to lift a 2500 kg weight by putting a weight of $25 \mathrm{kg}$ on a piston with a diameter of $10 \mathrm{cm} .$ Determine the diameter of the piston on which the weight is to be placed.

Mayukh Banik
Mayukh Banik
Numerade Educator
01:40

Problem 92

The efficiency of a refrigerator increases by 3 percent for each $^{\circ} \mathrm{C}$ rise in the minimum temperature in the device. What is the increase in the efficiency for each $(a) \mathrm{K}$ $(b)^{\circ} \mathrm{F},$ and $(c) \mathrm{R}$ rise in temperature?

Keshav Singh
Keshav Singh
Numerade Educator
00:30

Problem 93

Hyperthermia of $5^{\circ} \mathrm{C}$ (i.e., $5^{\circ} \mathrm{C}$ rise above the normal body temperature) is considered fatal. Express this fatal level of hyperthermia in $(a) \mathrm{K},(b)^{\circ} \mathrm{F},$ and $(c) \mathrm{R}$

Mayukh Banik
Mayukh Banik
Numerade Educator
01:00

Problem 94

A house is losing heat at a rate of $1800 \mathrm{kJ} / \mathrm{h}$ per $^{\circ} \mathrm{C}$ temperature difference between the indoor and the outdoor temperatures. Express the rate of heat loss from this house per $(a) \mathrm{K},(b)^{\circ} \mathrm{F},$ and $(c) \mathrm{R}$ difference between the indoor and the outdoor temperature.

Mayukh Banik
Mayukh Banik
Numerade Educator
00:44

Problem 95

The average temperature of the atmosphere in the world is approximated as a function of altitude by the relation $$T_{\mathrm{atm}}=288.15-6.5 z$$ where $T_{\mathrm{atm}}$ is the temperature of the atmosphere in $\mathrm{K}$ and $z$ is the altitude in $\mathrm{km}$ with $z=0$ at sea level. Determine the average temperature of the atmosphere outside an airplane that is cruising at an altitude of $12,000 \mathrm{m}$

Mayukh Banik
Mayukh Banik
Numerade Educator
01:05

Problem 96

Joe Smith, an old-fashioned engineering student, believes that the boiling point of water is best suited for use as the reference point on temperature scales. Unhappy that the boiling point corresponds to some odd number in the current absolute temperature scales, he has proposed a new absolute temperature scale that he calls the Smith scale. The temperature unit on this scale is $\operatorname{smith},$ denoted by $\mathrm{S},$ and the boiling point of water on this scale is assigned to be 1000 S. From a thermodynamic point of view, discuss if it is an acceptable temperature scale. Also, determine the ice point of water on the Smith scale and obtain a relation between the
Smith and Celsius scales.

Mayukh Banik
Mayukh Banik
Numerade Educator
02:07

Problem 97

It is well-known that cold air feels much colder in windy weather than what the thermometer reading indicates because of the "chilling effect" of the wind. This effect is due to the increase in the convection heat transfer coefficient with increasing air velocities. The equivalent wind chill temperature in $^{\circ} \mathrm{F}$ is given by $[\mathrm{ASHRAE},$ Handbook of Fundamentals (Atlanta, GA, $1993 \text { ), p. } 8.15]$ $$\begin{aligned}
T_{\mathrm{equiv}}=& 91.4-\left(91.4-T_{\text {anbient }}\right) \\
& \times(0.475-0.0203 V+0.304 \sqrt{V})
\end{aligned}$$
where $V$ is the wind velocity in $\mathrm{mi} / \mathrm{h}$ and $T_{\text {ambicnt }}$ is the ambient air temperature in $^{\circ} \mathrm{F}$ in calm air, which is taken to be air with light winds at speeds up to $4 \mathrm{mi} / \mathrm{h}$. The constant $91.4^{\circ} \mathrm{F}$ in the given equation is the mean skin temperature of a resting person in a comfortable environment. Windy air at temperature $T_{\text {ambient }}$ and velocity $V$ will feel as cold as the calm air at temperature $T_{\text {equiv. }}$ Using proper conversion factors, obtain an equivalent relation in SI units where $V$ is the wind velocity in $\mathrm{km} / \mathrm{h}$ and $T_{\text {ambient }}$ is the ambient air temperature in $^{\circ} \mathrm{C}$

Mayukh Banik
Mayukh Banik
Numerade Educator
00:51

Problem 98

Reconsider Prob. $1-97 \mathrm{E}$. Using EES (or other) software, plot the equivalent wind chill temperatures in $^{\circ} \mathrm{F}$ as a function of wind velocity in the range of 4 to 40 mph for the ambient temperatures of $20,40,$ and $60^{\circ} \mathrm{F}$. Discuss the results.

Mayukh Banik
Mayukh Banik
Numerade Educator
01:07

Problem 99

A vertical piston-cylinder device contains a gas at a pressure of 100 kPa. The piston has a mass of 5 kg and a diameter of $12 \mathrm{cm} .$ Pressure of the gas is to be increased by placing some weights on the piston. Determine the local atmospheric pressure and the mass of the weights that will double the pressure of the gas inside the cylinder.

Mayukh Banik
Mayukh Banik
Numerade Educator
00:39

Problem 100

An air-conditioning system requires a 35 -m-long section of 15 -cm diameter duct work to be laid underwater. Determine the upward force the water will exert on the duct. Take the densities of air and water to be $1.3 \mathrm{kg} / \mathrm{m}^{3}$ and $1000 \mathrm{kg} / \mathrm{m}^{3},$ respectively.

Mayukh Banik
Mayukh Banik
Numerade Educator
00:39

Problem 101

The average body temperature of a person rises by about $2^{\circ} \mathrm{C}$ during strenuous exercise. What is the rise in the body temperature in $(a) \mathrm{K},(b)^{\circ} \mathrm{F},$ and $(c) \mathrm{R}$ during strenuous exercise?

Mayukh Banik
Mayukh Banik
Numerade Educator
03:35

Problem 102

Balloons are often filled with helium gas because it weighs only about one-seventh of what air weighs under identical conditions. The buoyancy force, which can be expressed as $F_{b}=\rho_{\text {air }} g V_{\text {balloon }},$ will push the balloon upward. If the balloon has a diameter of $12 \mathrm{m}$ and carries two people, $85 \mathrm{kg}$ each, determine the acceleration of the balloon when it is first released. Assume the density of air is $\rho=1.16 \mathrm{kg} / \mathrm{m}^{3},$ and neglect the weight of the ropes and the cage.

Mayukh Banik
Mayukh Banik
Numerade Educator
03:12

Problem 103

Reconsider Prob. $1-102 .$ Using EES (or other) software, investigate the effect of the number of people carried in the balloon on acceleration. Plot the acceleration against the number of people, and discuss the results.

Hariprasad Annamalai
Hariprasad Annamalai
Numerade Educator
00:52

Problem 104

Determine the maximum amount of load, in $\mathrm{kg},$ the balloon described in Prob. $1-102$ can carry.

Mayukh Banik
Mayukh Banik
Numerade Educator
01:36

Problem 105

The lower half of a 6 -m-high cylindrical container is filled with water $\left(\rho=1000 \mathrm{kg} / \mathrm{m}^{3}\right)$ and the upper half with oil that has a specific gravity of $0.85 .$ Determine the pressure difference between the top and bottom of the cylinder.

Mayukh Banik
Mayukh Banik
Numerade Educator
01:43

Problem 106

A vertical, frictionless piston-cylinder device contains a gas at $180 \mathrm{kPa}$ absolute pressure. The atmospheric pressure outside is $100 \mathrm{kPa}$, and the piston area is $25 \mathrm{cm}^{2}$ Determine the mass of the piston.

Mayukh Banik
Mayukh Banik
Numerade Educator
00:43

Problem 107

A pressure cooker cooks a lot faster than an ordinary pan by maintaining a higher pressure and temperature inside. The lid of a pressure cooker is well sealed, and steam can escape only through an opening in the middle of the lid. A separate metal piece, the petcock, sits on top of this opening and prevents steam from escaping until the pressure force overcomes the weight of the petcock. The periodic escape of the steam in this manner prevents any potentially dangerous pressure buildup and keeps the pressure inside at a constant value. Determine the mass of the petcock of a pressure cooker whose operation pressure is 100 kPa gage and has an opening cross-sectional area of $4 \mathrm{mm}^{2}$. Assume an atmospheric pressure of $101 \mathrm{kPa}$, and draw the free-body diagram of the petcock.

Mayukh Banik
Mayukh Banik
Numerade Educator
00:51

Problem 108

A glass tube is attached to a water pipe, as shown in Fig. $P 1-108 .$ If the water pressure at the bottom of the tube is $110 \mathrm{kPa}$ and the local atmospheric pressure is $99 \mathrm{kPa}$, determine how high the water will rise in the tube, in $\mathrm{m}$. Take the density of water to be $1000 \mathrm{kg} / \mathrm{m}^{3}$

Mayukh Banik
Mayukh Banik
Numerade Educator
02:34

Problem 109

Consider a U-tube whose arms are open to the atmosphere. Now equal volumes of water and light oil $(\rho=$ $49.3 \mathrm{lbm} / \mathrm{ft}^{3}$ ) are poured from different arms. A person blows from the oil side of the U-tube until the contact surface of the two fluids moves to the bottom of the U-tube, and thus the liquid levels in the two arms are the same. If the fluid height in each arm is 30 in, determine the gage pressure the person exerts on the oil by blowing.

Mayukh Banik
Mayukh Banik
Numerade Educator
02:01

Problem 110

The basic barometer can be used as an altitudemeasuring device in airplanes. The ground control reports a barometric reading of $753 \mathrm{mmHg}$ while the pilot's reading is $690 \mathrm{mmHg} .$ Estimate the altitude of the plane from ground level if the average air density is $1.20 \mathrm{kg} / \mathrm{m}^{3}$.

Mayukh Banik
Mayukh Banik
Numerade Educator
09:50

Problem 111

A water pipe is connected to a double-U manometer as shown in Fig. $\mathrm{P} 1-111 \mathrm{E}$ at a location where the local atmospheric pressure is 14.2 psia. Determine the absolute pressure at the center of the pipe.

Mukesh Devi
Mukesh Devi
Numerade Educator
02:28

Problem 112

A gasoline line is connected to a pressure gage through a double-U manometer, as shown in Fig. $\mathrm{P} 1-112$ on the next page. If the reading of the pressure gage is $370 \mathrm{kPa}$ determine the gage pressure of the gasoline line.

Mayukh Banik
Mayukh Banik
Numerade Educator
00:27

Problem 113

Repeat Prob. $1-112$ for a pressure gage reading of $180 \mathrm{kPa}$

Mayukh Banik
Mayukh Banik
Numerade Educator
02:13

Problem 114

The average atmospheric pressure on earth is approximated as a function of altitude by the relation $P_{\mathrm{atm}}=$ $101.325(1-0.02256 z)^{5.256},$ where $P_{\text {atm }}$ is the atmospheric pressure in $\mathrm{kPa}$ and $z$ is the altitude in $\mathrm{km}$ with $z=0$ at sea level. Determine the approximate atmospheric pressures at Atlanta $(z=306 \mathrm{m}),$ Denver $(z=1610 \mathrm{m}),$ Mexico City $(z=2309 \mathrm{m}),$ and the top of Mount Everest $(z=8848 \mathrm{m})$

Mayukh Banik
Mayukh Banik
Numerade Educator
06:28

Problem 115

It is well-known that the temperature of the atmosphere varies with altitude. In the troposphere, which extends to an altitude of $11 \mathrm{km},$ for example, the variation of temperature can be approximated by $T=T_{0}-\beta z,$ where $T_{0}$ is the temperature at sea level, which can be taken to be $288.15 \mathrm{K},$ and $\beta=$ $0.0065 \mathrm{K} / \mathrm{m} .$ The gravitational acceleration also changes with altitude as $g(z)=g_{0} /(1+z / 6,370,320)^{2}$ where $g_{0}=9.807 \mathrm{m} / \mathrm{s}^{2}$ and $z$ is the elevation from sea level in $\mathrm{m}$. Obtain a relation for the variation of pressure in the troposphere ( $a$ ) by ignoring and (b) by considering the variation of $g$ with altitude.

Hariprasad Annamalai
Hariprasad Annamalai
Numerade Educator
03:01

Problem 116

The variation of pressure with density in a thick gas layer is given by $P=C \rho^{n}$, where $C$ and $n$ are constants. Noting that the pressure change across a differential fluid layer of thickness $d z$ in the vertical $z$ -direction is given as $d P=-\rho g d z,$ obtain a relation for pressure as a function of elevation $z .$ Take the pressure and density at $z=0$ to be $P_{0}$ and $\rho_{0},$ respectively.

Hariprasad Annamalai
Hariprasad Annamalai
Numerade Educator
02:12

Problem 117

Consider the flow of air through a wind turbine whose blades sweep an area of diameter $D$ (in $\mathrm{m}$ ). The average air velocity through the swept area is $V$ (in $\mathrm{m} / \mathrm{s}$ ). On the bases of the units of the quantities involved, show that the mass flow rate of air (in $\mathrm{kg} / \mathrm{s}$ ) through the swept area is proportional to air density, the wind velocity, and the square of the diameter of the swept area.

Mayukh Banik
Mayukh Banik
Numerade Educator
02:30

Problem 118

The drag force exerted on a car by air depends on a dimensionless drag coefficient, the density of air, the car velocity, and the frontal area of the car. That is, $F_{D}=$ function $\left(C_{\text {Drag }} A_{\text {front },} \rho, V\right) .$ Based on unit considerations alone, obtain a relation for the drag force.

Mayukh Banik
Mayukh Banik
Numerade Educator
01:02

Problem 119

An apple loses $4.5 \mathrm{kJ}$ of heat as it cools per $^{\circ} \mathrm{C}$ drop in its temperature. The amount of heat loss from the apple per $^{\circ} \mathrm{F}$ drop in its temperature is
$(a) 1.25 \mathrm{kJ}$
$(b) 2.50 \mathrm{kJ}$
$(c) 5.0 \mathrm{kJ}$
$(d) 8.1 \mathrm{kJ}$
$(e) 4.1 \mathrm{kJ}$

Mayukh Banik
Mayukh Banik
Numerade Educator
00:30

Problem 120

Consider a fish swimming $5 \mathrm{m}$ below the free surface of water. The increase in the pressure exerted on the fish when it dives to a depth of $25 \mathrm{m}$ below the free surface is
$(a) 196 \mathrm{Pa}$
$(b) 5400 \mathrm{Pa}$
$(c) 30,000 \mathrm{Pa}$
$(d) 196,000 \mathrm{Pa}$
$(e) 294,000 \mathrm{Pa}$

Mayukh Banik
Mayukh Banik
Numerade Educator
00:47

Problem 121

The atmospheric pressures at the top and the bottom of a building are read by a barometer to be 96.0 and $98.0 \mathrm{kPa}$ If the density of air is $1.0 \mathrm{kg} / \mathrm{m}^{3},$ the height of the building is
$(a) 17 \mathrm{m}$
(b) $20 \mathrm{m}$
$(c) 170 \mathrm{m}$
$(d) 204 \mathrm{m}$
$(e) 252 \mathrm{m}$

Mayukh Banik
Mayukh Banik
Numerade Educator
00:50

Problem 122

Consider a $2-\mathrm{m}$ deep swimming pool. The pressure difference between the top and bottom of the pool is
$(a) 12.0 \mathrm{kPa}$
$(b) 19.6 \mathrm{kPa}$
$(c) 38.1 \mathrm{kPa}$
$(d) 50.8 \mathrm{kPa}$
$(e) 200 \mathrm{kPa}$

Mayukh Banik
Mayukh Banik
Numerade Educator
00:33

Problem 123

During a heating process, the temperature of an object rises by $10^{\circ} \mathrm{C}$. This temperature rise is equivalent to a temperature rise of
$(a) 10^{\circ} \mathrm{F}$
$(b) 42^{\circ} \mathrm{F}$
$(c) 18 \mathrm{K}$
$(d) 18 \mathrm{R}$
$(e) 283 \mathrm{K}$

Mayukh Banik
Mayukh Banik
Numerade Educator
00:35

Problem 124

At sea level, the weight of 1 kg mass in SI units is 9.81 N. The weight of 1 lbm mass in English units is
$(a) 1 \mathrm{lbf}$
$(b) 9.81 \mathrm{lbf}$
$(c) 32.2 \mathrm{lbf}$
$(d) 0.1 \mathrm{lbf}$
$(e) 0.031 \mathrm{lbf}$

Mayukh Banik
Mayukh Banik
Numerade Educator
13:25

Problem 125

Write an essay on different temperature measurement devices. Explain the operational principle of each device, its advantages and disadvantages, its cost, and its range of applicability. Which device would you recommend for use in the following cases: taking the temperatures of patients in a doctor's office, monitoring the variations of temperature of a car engine block at several locations, and monitoring the temperatures in the furnace of a power plant?

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
00:58

Problem 126

Write an essay on the various mass- and volume-measurement devices used throughout history. Also, explain the development of the modern units for mass and volume.

Kerry Thornton-Genova
Kerry Thornton-Genova
Numerade Educator