College Physics
1st Edition
ISBN: 9781938168000
Author: Paul Peter Urone, Roger Hinrichs
Publisher: OpenStax College
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 15, Problem 8PE
(a) How long will the energy in a 1470−kJ (350−kcal) cup of yogurt last in a woman doing work at the rate of 150 W with an efficiency of 20.0% (such as in leisurely climbing stairs)? (b) Does the time found in part (a) imply that it is easy to consume more food energy than you can reasonably expect to work off with exercise?
Expert Solution & Answer
Trending nowThis is a popular solution!
Students have asked these similar questions
You use a quantity of fuel with a total energy content of 19.02 MJ to power an engine. If the average output of the engine over 2 hours was 2.12 kW, what is the efficiency of the engine?
A 68 kg cyclist is pedaling down the road at 15 km/h, using a total metabolic power of 480 W. A certain fraction of this energy is used to move the bicycle forward, but the balance ends up as thermal energy in his body, which he must get rid of to keep cool. On a very warm day, conduction, convection, and radiation transfer little energy, and so he does this by perspiring, with the evaporation of water taking away the excess thermal energy.
To keep from overheating, the cyclist must get rid of the excess thermal energy generated in his body. If he cycles at this rate for 2 hours, how many liters of water must he perspire, to the nearest 0.1 liter?A. 0.4 L B. 0.9 L C. 1.1 L D. 1.4 L
A 68 kg cyclist is pedaling down the road at 15 km/h, using a total metabolic power of 480 W. A certain fraction of this energy is used to move the bicycle forward, but the balance ends up as thermal energy in his body, which he must get rid of to keep cool. On a very warm day, conduction, convection, and radiation transfer little energy, and so he does this by perspiring, with the evaporation of water taking away the excess thermal energy.
As he cycles at a constant speed on level ground, at what rate is chemical energy being converted to thermal energy in his body, assuming a typical efficiency of 25% for the conversion of chemical energy to the mechanical energy of motion?A. 480 W B. 360 W C. 240 W D. 120 W
Chapter 15 Solutions
College Physics
Ch. 15 - Describe the photo of the tea kettle at the...Ch. 15 - The first law of thermodynamics and the...Ch. 15 - Heat transfer Q and work done W are always energy...Ch. 15 - How do heat transfer and internal energy differ?...Ch. 15 - If you run down some stairs and stop, what happens...Ch. 15 - Give an explanation of how food energy (calories)...Ch. 15 - Identify the type of energy transferred to your...Ch. 15 - A great deal of effort time, and money has been...Ch. 15 - One method of converting heat transfer to doing...Ch. 15 - Would the previous question make any sense for an...
Ch. 15 - We ordinarily say that U=0 for an isothermal...Ch. 15 - The temperature of a rapidly expanding gas...Ch. 15 - Which cyclical process represented by the two...Ch. 15 - A real process may be nearly adiabatic if it...Ch. 15 - It is unlikely that a process can be isothermal...Ch. 15 - Imagine you are driving a car up Pike’s Peak in...Ch. 15 - Is a temperature difference necessary to operate a...Ch. 15 - Definitions of efficiency vary depending on how...Ch. 15 - Whyother than the fact that the second law of...Ch. 15 - Think about the drinking bird at the beginning of...Ch. 15 - Can improved engineering and materials be employed...Ch. 15 - Does the second law of thermodynamics alter the...Ch. 15 - Explain why heat pumps do not work as well in very...Ch. 15 - In some Northern European nations, homes are being...Ch. 15 - Why do refrigerators, air conditioners, and heat...Ch. 15 - Grocery store managers contend that there is less...Ch. 15 - Can you cool a kitchen by leaving the refrigerator...Ch. 15 - A woman shuts her summer cottage up in September...Ch. 15 - Consider a system with a certain energy content,...Ch. 15 - Does a gas become more orderly when it liquefies?...Ch. 15 - Explain how water’s entropy can decrease when it...Ch. 15 - Is a uniform-temperature gas more or less orderly...Ch. 15 - Give an example of a spontaneous process in which...Ch. 15 - What is the change in entropy in an adiabatic...Ch. 15 - Does the entropy at a star increase or decrease as...Ch. 15 - Explain why a building made of bricks has smaller...Ch. 15 - Explain why a building made of bricks has smaller...Ch. 15 - What is the change in internal energy of a car if...Ch. 15 - How much heat transfer occurs from a system, if...Ch. 15 - A system does 1.80108J of work while 7.50108J of...Ch. 15 - What is the change in internal energy of a system...Ch. 15 - Suppose a woman does 500 J of work and 9500 J of...Ch. 15 - (a) How much food energy will a man metabolize in...Ch. 15 - (a) What is the average metabolic rate in watts of...Ch. 15 - (a) How long will the energy in a 1470kJ (350kcal)...Ch. 15 - (a) A woman climbing the Washington Monument...Ch. 15 - A car tire contains 0.0380m3 S of air at a...Ch. 15 - A heliumfilled toy balloon has a gauge pressure of...Ch. 15 - Steam to drive an old—fashioned steam locomotive...Ch. 15 - A hand—driven tire pump has a piston with a 2.50cm...Ch. 15 - Calculate the net work output of a heat engine...Ch. 15 - What is the net work output of a heat engine that...Ch. 15 - Unreasonable Results What is wrong with the claim...Ch. 15 - (a) A cyclical heat engine, operating between...Ch. 15 - Construct Your Own Problem Consider a car's...Ch. 15 - Construct Your Own Problem Consider a car trip...Ch. 15 - A certain heat engine does 10.0 kJ of work and...Ch. 15 - With 2.56106J of heat transfer into this engine, a...Ch. 15 - (a) What is the work output of a cyclical heat...Ch. 15 - (a) What is the eficiency of a cyclical heat...Ch. 15 - The engine of a large Ship does 2.00108J of work...Ch. 15 - (a) How much heat transfer occurs to the...Ch. 15 - Assume that the turbines at a coal—powered power...Ch. 15 - This problem compares the energy output and heat...Ch. 15 - A certain gasoline engine has an efficiency of...Ch. 15 - A gascooled nuclear reactor operates between hot...Ch. 15 - (a) What is the hot reservoir temperature of a...Ch. 15 - Steam locomotives have an efficiency of 17.0% and...Ch. 15 - Practical steam engines utilize 450C steam, which...Ch. 15 - A coalfired electrical power station has an...Ch. 15 - Would you be willing to financially back an...Ch. 15 - Unreasonable Results (a) Suppose you want to...Ch. 15 - Unreasonable Results Calculate the cold reservoir...Ch. 15 - What is the coefficient of performance of an ideal...Ch. 15 - Suppose you have an ideal refrigerator that cools...Ch. 15 - What is the best coefficient of performance...Ch. 15 - In a very mild winter climate, a heat pump has...Ch. 15 - (a) What is the best coefficient of performance...Ch. 15 - (a) What is the best coefficient of performance...Ch. 15 - Suppose you want to operate an ideal refrigerator...Ch. 15 - An ideal heat pump is being considered for use in...Ch. 15 - A 4ton air conditioner removes 5.60107J (48,000...Ch. 15 - Show that the coefficients of performance of...Ch. 15 - (a) On a winter day, a certain house loses...Ch. 15 - On a hot summer day, 4.00106J of heat transfer...Ch. 15 - A hot rock ejected from a volcano's lava fountain...Ch. 15 - When 1.60105J of heat transfer occurs into a meat...Ch. 15 - The Sun radiates energy at the rate of 3.801026W...Ch. 15 - (a) In reaching equilibrium, how much heat...Ch. 15 - What is the decrease in entropy of 25.0 g of water...Ch. 15 - Find the increase in entropy of 1.00 kg of liquid...Ch. 15 - A large electrical power station generates 1000 MW...Ch. 15 - (a) How much heat transfer occurs from 20.0 kg of...Ch. 15 - Using Table 15.4, verify the contention that if...Ch. 15 - What percent of the time will you get something in...Ch. 15 - (a) If tossing 100 coins, how many ways...Ch. 15 - (a) What is the change in entropy if you start...Ch. 15 - (a) What is the change in entropy if you start...Ch. 15 - (a) If you toss 10 coins, what percent of the time...Ch. 15 - (a) Construct a table showing the macro states and...Ch. 15 - In an air conditioner, 12.65 MJ of heat transfer...
Additional Science Textbook Solutions
Find more solutions based on key concepts
If acceleration is proportional to the net force or is equal to net force.
Conceptual Physics (12th Edition)
The proton is a composite particle composed of three quarks, all of which are either up quarks (u; charge +23e)...
Essential University Physics: Volume 2 (3rd Edition)
1. If an object is not moving, does that mean that there are no forces acting on it? Explain.
College Physics: A Strategic Approach (4th Edition)
2. A kidnapper demands a 40.0 kg cube of platinum as a ransom. What is the length of a side?
College Physics (10th Edition)
1. If an object is not moving, does that mean that there are no forces acting on it? Explain.
College Physics: A Strategic Approach (3rd Edition)
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
- Water falls over a dam of height h with a mass flow rate of R, in units of kilograms per second. (a) Show that the power available from the water is P=Rgh where g is the free-fall acceleration. (b) Each hydroelectric unit at the Grand Coulee Dam takes in water at a rate of 8.50 105 kg/s from a height of 87.0 m. The power developed by the falling water is converted to electric power with an efficiency of 85.0%. How much electric power does each hydroelectric unit produce?arrow_forwardA 68 kg cyclist is pedaling down the road at 15 km/h, using a total metabolic power of 480 W. A certain fraction of this energy is used to move the bicycle forward, but the balance ends up as thermal energy in his body, which he must get rid of to keep cool. On a very warm day, conduction, convection, and radiation transfer little energy, and so he does this by perspiring, with the evaporation of water taking away the excess thermal energy. If the cyclist reaches his 15 km/h cruising speed by rolling down a hill, what is the approximate height of the hill?A. 22 m B. 11 m C. 2 m D. 1 marrow_forwardSuppose that the breakfast of a typical 65 kg adult gives him 1.85 x 105 J of energy. How long does he have to do push-ups to burn at least 50 percent of this energy?arrow_forward
- Suppose a 10.00-kg mass drops through a height difference of 3.00 m, and the resulting work is used to turn a paddle in 200.0 g water, initially at 15.00°C. The final water temperature is found to be 15.35°C. Assuming that the work done is used entirely to increase the water temperature, calculate the conversion factor between joules and calories.arrow_forwardAn inventor claims to have developed a heat pump that produces a 200-kW heating effect for a 293 K heated zone while only using 75 kW of power and a heat source at 273 K. Justify the validity of this claim.arrow_forwardHow long in minutes will the energy in an 862 kJ (206 kcal) cup of yogurt last in a woman doing work at the rate of 110 W with an efficiency of 20.0% (such as in leisurely climbing stairs)? _____ minarrow_forward
- In a steam generator, a 4.7 m3 of water enters at a velocity 15m/s , 750 kpa and Internal energy of 550 kJ and leaves at 1216 kPa, 250 m/s , internal energy of 900 kJ and a volume of 6.0 m3 . Solve for the amount of heat absorbed by the water.arrow_forwardBy how much must one lower the temperature of a 65 – g of aluminum to change its internal energy by 350 J? Neglect any volume change.arrow_forwardIn an industrial process, a fuel-air mixture is fitted with a piston. When the mixture is ignited at a constant pressure of 700mm Hg, 2.0 kJ of energy is released and is found to occupy a final volume of 200L. What would be the initial volume occupied by the mixture if all energy released is converted as work done by the system to push the piston?arrow_forward
- A weightlifter curls a 28 kg bar, raising it each time a distance of 0.55 m. How many times must he repeat this exercise to burn off the energy in one slice of pizza? Assume 25% efficiency. Energy content of one slice of pizza is 1260 kJ.arrow_forwardA bricklayer drops a lump of mortar from a point 30 meters up the side of a brick building he is working on and it hits the ground with a splat. Mortar has a specificheat of 1200J/(kg•K). Byhow many degrees will the mortar be warmer, assuming that all the energy it acquires dur ing the drop is converted to internal energy inside the mortar and not the ground?arrow_forwardA thermodynamic system undergoes a process in which its internal energy decreases by 500 J. If at the same time 220 J of work is done on the system, find the thermal energy transferred to or from it.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Physics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
Physics for Scientists and Engineers, Technology ...
Physics
ISBN:9781305116399
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning
Principles of Physics: A Calculus-Based Text
Physics
ISBN:9781133104261
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning