Physics for Scientists and Engineers with Modern Physics
10th Edition
ISBN: 9781337671729
Author: SERWAY
Publisher: Cengage
expand_more
expand_more
format_list_bulleted
Concept explainers
Question
Chapter 19, Problem 26P
To determine
The reason for the necessity of blood flow to cool the man’s body by calculating the rate of energy
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
The rate at which a resting person converts food energy is called one’s basal metabolic rate (BMR). Assume that the resulting internal energy leaves a person’s body by radiation and convection of dry air. When you jog, most of the food energy you burn above your BMR becomes internalenergy that would raise your body temperature if it were not eliminated. Assume that evaporation of perspiration is the mechanism for eliminating this energy. Suppose a person is jogging for “maximum fat burning,” converting food energy at the rate 400 kcal/h above his BMR, and putting out energy by work at the rate 60.0 W. Assume that the heat of evaporation of water at body temperature is equal to its heat of vaporization at 100°C. (a) Determine the hourly rate at which water must evaporate from his skin. (b) When you metabolize fat, the hydrogen atoms in the fat molecule are transferred to oxygen to form water. Assume that metabolism of 1.00 g of fat generates 9.00 kcal of energy and produces 1.00 g of…
A person's basal metabolic rate (BMR) is the rate at which energy is expended while resting in a neutrally temperate environment. A typical BMR is 7.22 x 10° J/day. Convert this
BMR to units of watts and kilocalories (or Calories) per hour.
HINT
(a) watts
W
(b) kilocalories per hour
kcal/h
(c)
Suppose a 1.00 kg object's gravitation potential energy is increased at a rate equal to this typical BMR. Find the rate of change of the object's height in m/s. (The
acceleration of gravity is g = 9.80 m/s2.)
m/s
Overall, 80% of the energy used by the body must be eliminated as excess thermal energy and needs to be dissipated. The
mechanisms of elimination are radiation, evaporation of sweat (2,430 kJ/kg), evaporation from the lungs (38 kJ/h),
conduction, and convection.
A person working out in a gym has a metabolic rate of 2,500 kJ/h. His body temperature is 37°C, and the outside
temperature 22°C. Assume the skin has an area of 2.0 m2 and emissivity of 0.97. (o = 5.6696 × 10-8 w/m2 · K4)
(a) At what rate is his excess thermal energy dissipated by radiation? (Enter your answer to at least one decimal
place.)
1.8e2
W
(b) If he eliminates 0.44 kg of perspiration during that hour, at what rate is thermal energy dissipated by
evaporation of sweat? (Enter your answer to at least one decimal place.)
3.0e2
W
(c) At what rate is energy eliminated by evaporation from the lungs? (Enter your answer to at least one decimal
place.)
10.6
W
(d) At what rate must the remaining excess energy be eliminated…
Chapter 19 Solutions
Physics for Scientists and Engineers with Modern Physics
Ch. 19.2 - Prob. 19.1QQCh. 19.3 - Prob. 19.2QQCh. 19.5 - Prob. 19.3QQCh. 19.5 - Characterize the paths in Figure 19.12 as...Ch. 19.6 - Prob. 19.5QQCh. 19 - Prob. 1PCh. 19 - The highest waterfall in the world is the Salto...Ch. 19 - Prob. 3PCh. 19 - The temperature of a silver bar rises by 10.0C...Ch. 19 - You are working in your kitchen preparing lunch...
Ch. 19 - If water with a mass mk at temperature Tk is...Ch. 19 - Prob. 7PCh. 19 - An electric drill with a steel drill bit of mass m...Ch. 19 - Prob. 9PCh. 19 - How much energy is required to change a 40.0-g ice...Ch. 19 - Prob. 11PCh. 19 - Prob. 12PCh. 19 - In an insulated vessel, 250 g of ice at 0C is...Ch. 19 - Prob. 14PCh. 19 - One mole of an ideal gas is warmed slowly so that...Ch. 19 - (a) Determine the work done on a gas that expands...Ch. 19 - A thermodynamic system undergoes a process in...Ch. 19 - Prob. 18PCh. 19 - A 2.00-mol sample of helium gas initially at 300...Ch. 19 - (a) How much work is done on the steam when 1.00...Ch. 19 - A 1.00-kg block of aluminum is warmed at...Ch. 19 - In Figure P19.22, the change in internal energy of...Ch. 19 - Prob. 23PCh. 19 - A concrete slab is 12.0 cm thick and has an area...Ch. 19 - Two lightbulbs have cylindrical filaments much...Ch. 19 - Prob. 26PCh. 19 - (a) Calculate the R-value of a thermal window made...Ch. 19 - Prob. 28PCh. 19 - Gas in a container is at a pressure of 1.50 atm...Ch. 19 - Prob. 30APCh. 19 - You have a particular interest in automobile...Ch. 19 - Prob. 32APCh. 19 - Prob. 33APCh. 19 - Prob. 34APCh. 19 - Review. Following a collision between a large...Ch. 19 - Prob. 36APCh. 19 - An ice-cube tray is filled with 75.0 g of water....Ch. 19 - Prob. 38APCh. 19 - An iron plate is held against an iron wheel so...Ch. 19 - One mole of an ideal gas is contained in a...Ch. 19 - Prob. 41APCh. 19 - Prob. 42APCh. 19 - Prob. 43APCh. 19 - A student measures the following data in a...Ch. 19 - (a) The inside of a hollow cylinder is maintained...Ch. 19 - Prob. 46CPCh. 19 - Prob. 47CP
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- If a gas is compressed isothermally, which of the following statements is true? (a) Energy is transferred into the gas by heat. (b) No work is done on the gas. (c) The temperature of the gas increases. (d) The internal energy of the gas remains constant. (e) None of those statements is true.arrow_forwardOverall, 80% of the energy used by the body must be eliminated as excess thermal energy and needs to be dissipated. The mechanisms of elimination are radiation, evaporation of sweat (2,430 kJ/kg), evaporation from the lungs (38 kJ/h), conduction, and convection.A person working out in a gym has a metabolic rate of 2,500 kJ/h. His body temperature is 37°C, and the outside temperature 26°C. Assume the skin has an area of 2.0 m2 and emissivity of 0.97. (σ = 5.6696 10-8 W/m2 · K4) (a) At what rate is his excess thermal energy dissipated by radiation? (Enter your answer to at least one decimal place.) W(b) If he eliminates 0.44 kg of perspiration during that hour, at what rate is thermal energy dissipated by evaporation of sweat? (Enter your answer to at least one decimal place.) W(c) At what rate is energy eliminated by evaporation from the lungs? (Enter your answer to at least one decimal place.) W(d) At what rate must the remaining excess energy be eliminated through conduction and…arrow_forwardThe human body must maintain its core temperature inside a rather narrow range around 37°C. Metabolic processes, notably muscular exertion, convert potential energy into internal energy deep in the interior. From the interior, energy must flow out to the skin or lungs to be expelled to the environment. During moderate exercise, an 80-kg man can metabolize food energy at the rate 300 kcal/h, do 60 kcal/h of mechanical work, and put out the remaining 240 kcal/h of energy by heat. Most of the energy is carriedfrom the body interior out to the skin by forced convection, whereby blood is warmed in the interior and then cooled at the skin, which is a few degrees cooler than the body core. Without blood flow, living tissue is a good thermal insulator, with thermal conductivity about 0.210 W/m · °C. Show that blood flow is essential to cool the man’s body by calculatingthe rate of energy conduction in kcal/h through the tissue layer under his skin. Assume that its area is 1.40 m2, its…arrow_forward
- Compressed air can be pumped underground into huge caverns as a form of energy storage. The volume of a cavern is 6.3 x 105 m³, 5 and the pressure of the air in it is 7.4 × 106 Pa. Assume that air is a diatomic ideal gas whose internal energy U is given by U = nRT. If one home uses 30.0 kWh of energy per day, how many homes could this internal energy serve for one day?arrow_forwardA 46-kg woman eats a 522 Calorie (522 kcal) jelly doughnut for breakfast. (a) How many joules of energy are the equivalent of one jelly doughnut? 2192.4 X Your response is off by a multiple of ten. J (b) How many steps must the woman climb on a very tall stairway to change the gravitational potential energy of the woman-Earth system by a value equivalent to the food energy in one jelly doughnut? Assume the height of a single stair is 15 cm. 8.67 X Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. stairs (c) If the human body is only 26% efficient in converting chemical potential energy to mechanical energy, how many steps must the woman climb to work off her breakfast? 9 X Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. stairsarrow_forwardOverall, 80% of the energy used by the body must be eliminated as excess thermal energy and needs to be dissipated. The mechanisms of elimination are radiation, evaporation of sweat (2,430 kJ/kg), evaporation from the lungs (38 kJ/h), conduction, and convection. A person working out in a gym has a metabolic rate of 2,500 kJ/h. His body temperature is 37°C, and the outside 5.6696 x 10-8 W/m2 · K4) temperature 22°C. Assume the skin has an area of 2.0 m2 and emissivity of 0.97. (o %D (a) At what rate is his excess thermal energy dissipated by radiation? (Enter your answer to at least one decimal place.) 136.7 Your response differs from the correct answer by more than 10%. Double check your calculations. W (b) If he eliminates 0.44 kg of perspiration during that hour, at what rate is thermal energy dissipated by evaporation of sweat? (Enter your answer to at least one decimal place.) W (c) At what rate is energy eliminated by evaporation from the lungs? (Enter your answer to at least one…arrow_forward
- A weightlifter drinks a protein shake that contains 2.00 × 10² Calories. She then performs multiple repetitions on the bench press and does 2.75 x 105 J of work. After her workout, her net change in internal energy is +1.50 × 105 J. During her workout, she loses heat to the environment, which results in the vaporization of perspiration from the surface of her skin. What mass of water did she lose due to perspiration? Assume the latent heat of vaporization of the perspiration is 2.42 x 106 J/kg. Number Unitsarrow_forwardA 58-kg woman cheats on her diet and eats a 555-Calorie (555 kcal) jelly doughnut for breakfast. (a) How many joules of energy are the equivalent of one jelly doughnut? (b) How many stairs must the woman climb to perform an amount of mechanical work equivalent to the food energy in one jelly doughnut? Assume the height of a single stair is 15 cm. stairs (c) If the human body is only 26% efficient in converting chemical energy to mechanical energy, how many stairs must the woman climb to work off her breakfast? stairsarrow_forwardWhen energy shortages occur, magazine articles sometimes urge us to keep our homes at a constant temperature day and night to conserve fuel. They argue that when we turn down the heat at night, the walls, ceilings, and other areas cool off and must be reheated in the morning. So if we keep the temperature constant, these parts of the house will not cool off and will not have to be reheated. Does this argument make sense? Would we really save energy by following this advice?arrow_forward
- A 55-kg student eats a 540-Calorie (540 kcal) jelly doughnut for breakfast. (a) How many joules of energy are the equivalent of one jelly doughnut? (b) How many stairs must the student climb to perform an amount of mechanical work equivalent to the food energy in one jelly doughnut? Assume the height of a single stair is 15 cm. (c) If the human body is only 25% efficient in converting chemical energy to mechanical energy, how many stairs must the woman climb to work off her breakfast?arrow_forwardWhen someone has a fever, his or her body temperature might increase by as much as 2°C. Suppose this person has a mass of 48 kg. (a) About how much energy is required to raise a person’s temperature this much? The energy required to raise the person’s temperature is ___J (b) What is this energy in food calories? (1 food calorie ≡ 1 Cal ≡ 1000 calories = 1 kcal.) The energy in food calories is ___calarrow_forwardHow long does a 65 kg adult need to walk at a rate of 5 km/h in order to burn off all the energy in half slice of pizza. Each slice of pizza contains 1260 kJ of energy. The metabolic power for walking at 5 km/h is 380 W. O 27.6 min O 6.9 min O 55.3 min O 13.8 minarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax College
Principles of Physics: A Calculus-Based Text
Physics
ISBN:9781133104261
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning
College Physics
Physics
ISBN:9781938168000
Author:Paul Peter Urone, Roger Hinrichs
Publisher:OpenStax College