🏷️ LIMITED TIME OFFER: GET 20% OFF GRADE+ YEARLY SUBSCRIPTION →
Log in
Physics
1
answer
0
watching
518
views

Definitions of the efficiency vary depending on how energy is being converted. Compare the definitions of efficiency for the human body and heat engines. How does the definition of efficiency in each relate to the type of energy being converted into doing walk?

Watch
1
answer
0
watching
518
views

For unlimited access to Homework Help, a Homework+ subscription is required.

Avatar image
Liked by 712591289707307
Zubair Aslam
Zubair AslamLv8
4 Dec 2020

Unlock all answers

Get 1 free homework help answer.
Already have an account? Log in
Share

Related textbook solutions

Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

A firebox is at 750 K, and the ambient temperature is
300 K. The efficiency of a Carnot engine doing 150 J of work
as it transports energy between these constant- temperature
baths is 60.0%. The Carnot engine must take in energy
150 J/0.600 5 250 J from the hot reservoir and must put
out 100 J of energy by heat into the environment. To follow
Carnot’s reasoning, suppose some other heat engine
S could have an efficiency of 70.0%. (a) Find the energy
input and exhaust energy output of engine S as it does 150 J
of work. (b) Let engine S operate as in part (a) and run the
Carnot engine in reverse between the same reservoirs. The
output work of engine S is the input work for the Carnot
refrigerator. Find the total energy transferred to or from
the firebox and the total energy transferred to or from the
environment as both engines operate together. (c) Explain
how the results of parts (a) and (b) show that the Clausius
statement of the second law of thermodynamics is violated.
(d) Find the energy input and work output of engine S as it
puts out exhaust energy of 100 J. Let engine S operate as in
part (c) and contribute 150 J of its work output to running theCarnot engine in reverse. Find (e) the total energy the
firebox puts out as both engines operate together, (f) the
total work output, and (g) the total energy transferred to
the environment. (h) Explain how the results show that
the Kelvin–Planck statement of the second law is violated.
Therefore, our assumption about the efficiency of engine S
must be false. (i) Let the engines operate together through
one cycle as in part (d). Find the change in entropy of the
Universe. (j) Explain how the result of part (i) shows that
the entropy statement of the second law is violated.

The human body converts internal chemical energy into work andheatat rates of 60 to 125 W (called the basal metabolicrate).This energy comes from food and is usually measured inkilocalories[1 kcal = 4.186 kJ]. (Note that thenutritional `Calorie'listed on packaged food actually equals 1kilocalorie). How manykilocalories of food energy does a personwith a metoblic rate of105.0 W require per day? (Assume100 percent efficiency.)

Suppose a woman does of work and of heat transfer occurs into the environment in the process.

(a) What is the decrease in her internal energy, assuming no change in temperature or consumption of food? (That is, there is no other energy transfer.)

 

(b)

The internal energy is stored energy due to food intake. Treating the change in internal energy as the input energy and work done as output, what is her efficiency?

Efficiency: Eff:  

Weekly leaderboard

Home
Homework Help 3,900,000
Physics 110,000
Start filling in the gaps now
Log in