## Physlet Problems: Thermodynamics

Physlet problems that relate to thermodynamics.

Material Type:
Quiz/Test

Technical Format:
Java Applet

Date Added to MERLOT:
November 21, 2000

Date Modified in MERLOT:
November 21, 2000

Submitter:
Chuck
Bennett

### Quality

- Editor Review avg:
- User Rating:
- Discussion (6 Comments)
- Learning Exercises (none)
- Personal Collections (none)
- Accessibility Info (none)

### About

Primary Audience:
College General Ed

Mobile Compatibility:
Not specified at this time

Technical Requirements:
Physlets may be hosted locally and customized with javascript. Information and resources are available from the home page of the above site.

Language:
English

Cost Involved:
no

Source Code Available:
no

Accessiblity Information Available:
no

Copyright:
yes

Creative Commons:
unsure

### Connections

### Browse in Categories

### Discussion

## Discussion for Physlet Problems: Thermodynamics

Log in to participate in the discussions or Register if you are not already a MERLOT member.

13 years ago

### Franziska vonHerrath (Student)

8.12.1

This problem and its physlet animation is a good

attempt to visualize the fact that expansion through

heating is unique to each metal. However, the

animation could be improved by enlarging the

temperature scale, in order to provide for more

accuracy when estimating the temperature change in the

metal bar. Since it was mentioned what units position

and time were measured in, it could have been included

what units the temperature scale showed.

8.12.2

I enjoyed the animation of the growing bubble rising

to the surface of the liquid to burst. The counting

vertical position scale also aided in performing the

ratio computation. However, after carefully

performing the final to initial temperature ratio

calculation, I disagree with the featured result. I

calculated the ratio to be 6.05.

8.12.3

This animation clearly underlines the properties of

an ideal gas and is nicely done in a, however, purely

qualitative manner. Overall, I?m not sure that the

properties of an ideal gas need this kind of elaborate

illustration. Simple pictures would have sufficed.

8.12.4

The speed vs. time graph nicely illustrates the

changes in the speed of the molecules of the gaseous

substance but aids little in showing the average speed

of the molecules. This visualization could be improved

by displaying the average speed of the different

spheres at the end of the animation to assist in the

calculation of the average kinetic energy.

8.12.5

In this problem, a gas is compressed at constant

pressure and seemingly at the constant temperature of

0 *C. Since the container appears tight (no molecules

can escape), I can only ask how is this process

possible. The pressure should have been visualized in

a better manner. The gauge added more confusion than

it cleared up. More work needs to be done in order

for one to make sense of this problem.

Additional Problem 1)

I had a hard time changing the temperature of the gas

in theleft container in the running time provided.

The running time should be increased to counteract not

only this problem, but also in order for the system to

be allowed to come to equilibrium.

Additional Problem 2)

This physlet worked well and is a good illustration

of the distribution of speeds in a gas.

This site could benefit from a more detailed

description of the problems? initial conditions.

Furthermore, the given answers should be accompanied

by a few sentences of explanation. Overall, this site

needs serious improvement to warrant its use over or

even in addition to a generic textbook.

This problem and its physlet animation is a good

attempt to visualize the fact that expansion through

heating is unique to each metal. However, the

animation could be improved by enlarging the

temperature scale, in order to provide for more

accuracy when estimating the temperature change in the

metal bar. Since it was mentioned what units position

and time were measured in, it could have been included

what units the temperature scale showed.

8.12.2

I enjoyed the animation of the growing bubble rising

to the surface of the liquid to burst. The counting

vertical position scale also aided in performing the

ratio computation. However, after carefully

performing the final to initial temperature ratio

calculation, I disagree with the featured result. I

calculated the ratio to be 6.05.

8.12.3

This animation clearly underlines the properties of

an ideal gas and is nicely done in a, however, purely

qualitative manner. Overall, I?m not sure that the

properties of an ideal gas need this kind of elaborate

illustration. Simple pictures would have sufficed.

8.12.4

The speed vs. time graph nicely illustrates the

changes in the speed of the molecules of the gaseous

substance but aids little in showing the average speed

of the molecules. This visualization could be improved

by displaying the average speed of the different

spheres at the end of the animation to assist in the

calculation of the average kinetic energy.

8.12.5

In this problem, a gas is compressed at constant

pressure and seemingly at the constant temperature of

0 *C. Since the container appears tight (no molecules

can escape), I can only ask how is this process

possible. The pressure should have been visualized in

a better manner. The gauge added more confusion than

it cleared up. More work needs to be done in order

for one to make sense of this problem.

Additional Problem 1)

I had a hard time changing the temperature of the gas

in theleft container in the running time provided.

The running time should be increased to counteract not

only this problem, but also in order for the system to

be allowed to come to equilibrium.

Additional Problem 2)

This physlet worked well and is a good illustration

of the distribution of speeds in a gas.

This site could benefit from a more detailed

description of the problems? initial conditions.

Furthermore, the given answers should be accompanied

by a few sentences of explanation. Overall, this site

needs serious improvement to warrant its use over or

even in addition to a generic textbook.

13 years ago

### Ian Clark (Student)

This site appears to be comprised entirely of introductory physics problems

centered around java applets. The applets produce cartoons illustrating

different concepts from introductory kinetic, and thermodynamic theory. My

first impression was that the site was a little long on cartoons and a little

short on physics. I believe that the argument for these physics related java

cartoons (physlets) is that they build a sense of physical intuition in a more

expedient fashion than does the traditional approach to physics education.

While I do certainly respect this argument I felt this site sacrificed too much

of the traditional rigor and provided too little in return. In its defense, the

sight is an extension of an introductory physics text and when used in

conjunction with this text it may well be quite illuminating. As a stand-alone

educational tool however I would not give it high marks.

Mechanically the site was well constructed and easy to navigate. The only

serious difficulty I found was in measuring objects in the animation frame.

Many of the problems call for the viewer to measure the physical dimensions of

an object in the animation and I found this process to be somewhat onerous. On

all of the applets reviewed left clicking the mouse while the cursor is in the

frame of the animation displays the x, y coordinates of the cursor. This

provided an effective but cumbersome means of measurement, and the only other

option was to count the tiny grid lines. Even using a 19-inch monitor, I found

squinting at those tiny increments to be rather painful.

The page I viewed linked to five problems and two additional problems below I

review each of the first five in turn.

Problem 1.

Physical Principal Illustrated: the linear dependence of the thermal expansion

of solids on the change in temperature.

The Problem: three animations depict a little stick expanding as the temperature

rises from -50C to 0C (first animation), 0C to 50C(second animation), and 50C

to 100C (last animation). All sticks have the same initial and final length.

The viewer is asked if the three sticks are all the same material.

Review: This problem was well crafted in that it illustrated the dependence of

expansion on the change in temperature rather than the temperature its self (at

least at this level of theory). That being said I do have a fine point on which

to quibble. I personally would have replaced the phrase 'the same material'

with 'the same average coefficient of linear expansion'. Deciding that two

items are comprised of the same material because they have similar thermal

expansion characteristics seems somewhat analogous to deciding that a Ferrari is

made of the same material as a red delicious apple because they are roughly the

same color.

Problem 2

Physical Principal Illustrated: The ideal gas law

The Problem: A bubble rises from 5cm below the surface of the water to the

surface of the water. The viewer is asked to determine the ratio of final to

initial temperatures.

Review: I would really like to see something like 'expands adiabatically'

somewhere in the wording of this problem. The time frame is 1 second and as

such a lack of heat exchange with the water is probably a very good

approximation. Again this is a small point and in second semester physics the

possible error due to heat exchange would never have never crossed my mind.

I worked through this problem twice and I don't seem to be arriving at the same

answer that is presented on the page. The equation I derived was:

Tf/Ti = (Pf rf^3)/(Pi ri^3)

Where T, P, and r represent the temperature, pressure and the radius of the

bubble respectively, f indicates the final state and I indicates the initial

state. Using 101325 Pa and 101325 Pa + (density of H2O) (g) (h) for the final

and initial pressures and the dimensions given yields 18.2 rather than the 13.6

listed on the site. If I have made some error in mycalculations I would like

to be informed of the fact so that I can write a retraction. I can be contacted

at itc1@humboldt .edu.

Problem 3

Physical Principal Illustrated: the characteristics of the ideal gas.

The Problem: Three animations are displayed. The reader has to decide which

animation is depicting an ideal gas.

Review: Vibrantly illustrates the internal properties of an ideal gas i.e. no

interaction between particles, inter-particle distance is large with respect to

particle size, and perfectly elastic collisions with the container walls. This

was probably the most educationally effective use of applets I found on this

site.

Problem 4

Physical Principal Illustrated: the equal distribution of average kinetic

energy in a gas at thermal equilibrium.

The Problem: A Big ball, a medium ball, and a little ball (colored red, yellow

and green respectively) are depicted bouncing around with a bunch of other

little balls (these balls are, of course, a representation of molecules in a

gas). The speed of each of the three colored balls is displayed in a separate

chart. The viewer is asked to decide which of the colored balls has the

greatest average kinetic energy.

Review: Very clever way to make the point: at equilibrium individual molecules

in a gas will have the same average kinetic energy. The only problem was

estimating the average speed from the wildly erratic speed vs. time chart.

Problem 5

I am admittedly confused by this problem. A container of gas decreases in

volume, while both the pressure and temperature remain constant. The viewer is

asked to calculate the work done on the gas. I can only assume that there is a

gaping hole somewhere in the container or that the thermometer, and/or the

pressure gauge is broken. The prospect of solving a problem dealing with a

non-closed system and/or erroneous measurements is somewhat more daunting than I

would care to face in a freshman physics class.

In conclusion I wouldsay that this site certainly has some educational merit,

but it by no means inspired me to trade in my freshman text books for a few

mega-bytes of Java source code.

centered around java applets. The applets produce cartoons illustrating

different concepts from introductory kinetic, and thermodynamic theory. My

first impression was that the site was a little long on cartoons and a little

short on physics. I believe that the argument for these physics related java

cartoons (physlets) is that they build a sense of physical intuition in a more

expedient fashion than does the traditional approach to physics education.

While I do certainly respect this argument I felt this site sacrificed too much

of the traditional rigor and provided too little in return. In its defense, the

sight is an extension of an introductory physics text and when used in

conjunction with this text it may well be quite illuminating. As a stand-alone

educational tool however I would not give it high marks.

Mechanically the site was well constructed and easy to navigate. The only

serious difficulty I found was in measuring objects in the animation frame.

Many of the problems call for the viewer to measure the physical dimensions of

an object in the animation and I found this process to be somewhat onerous. On

all of the applets reviewed left clicking the mouse while the cursor is in the

frame of the animation displays the x, y coordinates of the cursor. This

provided an effective but cumbersome means of measurement, and the only other

option was to count the tiny grid lines. Even using a 19-inch monitor, I found

squinting at those tiny increments to be rather painful.

The page I viewed linked to five problems and two additional problems below I

review each of the first five in turn.

Problem 1.

Physical Principal Illustrated: the linear dependence of the thermal expansion

of solids on the change in temperature.

The Problem: three animations depict a little stick expanding as the temperature

rises from -50C to 0C (first animation), 0C to 50C(second animation), and 50C

to 100C (last animation). All sticks have the same initial and final length.

The viewer is asked if the three sticks are all the same material.

Review: This problem was well crafted in that it illustrated the dependence of

expansion on the change in temperature rather than the temperature its self (at

least at this level of theory). That being said I do have a fine point on which

to quibble. I personally would have replaced the phrase 'the same material'

with 'the same average coefficient of linear expansion'. Deciding that two

items are comprised of the same material because they have similar thermal

expansion characteristics seems somewhat analogous to deciding that a Ferrari is

made of the same material as a red delicious apple because they are roughly the

same color.

Problem 2

Physical Principal Illustrated: The ideal gas law

The Problem: A bubble rises from 5cm below the surface of the water to the

surface of the water. The viewer is asked to determine the ratio of final to

initial temperatures.

Review: I would really like to see something like 'expands adiabatically'

somewhere in the wording of this problem. The time frame is 1 second and as

such a lack of heat exchange with the water is probably a very good

approximation. Again this is a small point and in second semester physics the

possible error due to heat exchange would never have never crossed my mind.

I worked through this problem twice and I don't seem to be arriving at the same

answer that is presented on the page. The equation I derived was:

Tf/Ti = (Pf rf^3)/(Pi ri^3)

Where T, P, and r represent the temperature, pressure and the radius of the

bubble respectively, f indicates the final state and I indicates the initial

state. Using 101325 Pa and 101325 Pa + (density of H2O) (g) (h) for the final

and initial pressures and the dimensions given yields 18.2 rather than the 13.6

listed on the site. If I have made some error in mycalculations I would like

to be informed of the fact so that I can write a retraction. I can be contacted

at itc1@humboldt .edu.

Problem 3

Physical Principal Illustrated: the characteristics of the ideal gas.

The Problem: Three animations are displayed. The reader has to decide which

animation is depicting an ideal gas.

Review: Vibrantly illustrates the internal properties of an ideal gas i.e. no

interaction between particles, inter-particle distance is large with respect to

particle size, and perfectly elastic collisions with the container walls. This

was probably the most educationally effective use of applets I found on this

site.

Problem 4

Physical Principal Illustrated: the equal distribution of average kinetic

energy in a gas at thermal equilibrium.

The Problem: A Big ball, a medium ball, and a little ball (colored red, yellow

and green respectively) are depicted bouncing around with a bunch of other

little balls (these balls are, of course, a representation of molecules in a

gas). The speed of each of the three colored balls is displayed in a separate

chart. The viewer is asked to decide which of the colored balls has the

greatest average kinetic energy.

Review: Very clever way to make the point: at equilibrium individual molecules

in a gas will have the same average kinetic energy. The only problem was

estimating the average speed from the wildly erratic speed vs. time chart.

Problem 5

I am admittedly confused by this problem. A container of gas decreases in

volume, while both the pressure and temperature remain constant. The viewer is

asked to calculate the work done on the gas. I can only assume that there is a

gaping hole somewhere in the container or that the thermometer, and/or the

pressure gauge is broken. The prospect of solving a problem dealing with a

non-closed system and/or erroneous measurements is somewhat more daunting than I

would care to face in a freshman physics class.

In conclusion I wouldsay that this site certainly has some educational merit,

but it by no means inspired me to trade in my freshman text books for a few

mega-bytes of Java source code.

13 years ago

### Sheila Dodson (Student)

This site was designed with an introductory college physics student in mind, and

yet that is particularly the audience it would do the greatest diservice! The

physics behind the problems are left vague and sometimes even misleading. This

would only leave a student more confused and bewildered about the world of

thermodynamics. The benefits of Java applets are far outweighed by the poor

design of this site. I have outlined the problems the page poses to it's

audience and a critique therof:

Re: problem 8.12.1:

It is extraordinarily difficult for a student to see the answer, stated so

obvioulsy, because not only are the Java scripts slow and inexact, but also

because the programmer chose to make the student view the rods expansion one at

a time, instead of simultaneously. As a result it would be virtually impossible

for the student to measure each rod's length and calculate for themselves the

conclusion, that all the rods are the same.

Re: Problem 8.12.2:

This Java applet is well-programmed, but the proceedure by which the author used

to arrive at his conclusions are not well spelled out, leaving the students to

wonder what assumptions were employed to reach his answer. I personally could

not find the route he took to reach the given answer of 13.6.

Re: Problem 8.12.3:

Unlike the previous two applets this one is surprizingly well done and

instructive in that it gives the students a chance to not only see the behavior

of an ideal gas in real time but it also gives them a chance to think

crittically about how an ideal gas would behave compared to other gases. My

only critticism is that again it is not obvious how the author reached the

conclusions he did, and the applet runs so slowly that it is difficult to see

how interacting (or non-interacting the molecules are)

Re: Problem 8.12.4:

This applet is well done, and poses and interesting question to the students.

It shows the motion of three different size molecules and their respectivespeeds and asks, " which has the greatest kinetic energy" and replys that all

three of them tie. I like the fact that the problem was enginered such that the

answer was not the obvious one, and makes the student realize that the kinetic

energy is not just a fuction of speed, but also of mass. I would reccomend that

instead of displaying the instantaneous velocity of the particles that instead

the applet would display the average velocity such that the student could

realistically make the calculations.

Re: Problem 8.12.5:

I believe there is something broken in this java applet. The animation implies

that a container is decreasing in volume, yet maintaining a constant pressure

and temperature! This cannot be, so it's not only impossible for the student to

arrive at the same answer, but it can be confusing to students who thought they

understood compression and work, and now they see this animation that breaks

all the rules!

Additional Problem one:

I enjoyed this applet, although it is VERY SLOW to run, and even slower after

making the reccomended changes. Despite the technical difficulties it is a

wonderful illustration of the relationship between pressure and temperature, and

a great reminder for early physics students about the meaning of equilibrium.

Additional Problem Two:

This last applet is instructive, but too difficult to use. The question

concerns a box of O2 molecules, where the individual speeds of the molecules are

given. It wants to know the average speed of all the molecules. I suggest

that instead of having to continuously average the speeds of the 20 molecules

over the course of 20 seconds, the applet be reduced to somthing like 5

molecules. By doing so it makes it feasible that a student could actually

average the speeds and arrive at an answer. Leave the mass computing to the

computers!

yet that is particularly the audience it would do the greatest diservice! The

physics behind the problems are left vague and sometimes even misleading. This

would only leave a student more confused and bewildered about the world of

thermodynamics. The benefits of Java applets are far outweighed by the poor

design of this site. I have outlined the problems the page poses to it's

audience and a critique therof:

Re: problem 8.12.1:

It is extraordinarily difficult for a student to see the answer, stated so

obvioulsy, because not only are the Java scripts slow and inexact, but also

because the programmer chose to make the student view the rods expansion one at

a time, instead of simultaneously. As a result it would be virtually impossible

for the student to measure each rod's length and calculate for themselves the

conclusion, that all the rods are the same.

Re: Problem 8.12.2:

This Java applet is well-programmed, but the proceedure by which the author used

to arrive at his conclusions are not well spelled out, leaving the students to

wonder what assumptions were employed to reach his answer. I personally could

not find the route he took to reach the given answer of 13.6.

Re: Problem 8.12.3:

Unlike the previous two applets this one is surprizingly well done and

instructive in that it gives the students a chance to not only see the behavior

of an ideal gas in real time but it also gives them a chance to think

crittically about how an ideal gas would behave compared to other gases. My

only critticism is that again it is not obvious how the author reached the

conclusions he did, and the applet runs so slowly that it is difficult to see

how interacting (or non-interacting the molecules are)

Re: Problem 8.12.4:

This applet is well done, and poses and interesting question to the students.

It shows the motion of three different size molecules and their respectivespeeds and asks, " which has the greatest kinetic energy" and replys that all

three of them tie. I like the fact that the problem was enginered such that the

answer was not the obvious one, and makes the student realize that the kinetic

energy is not just a fuction of speed, but also of mass. I would reccomend that

instead of displaying the instantaneous velocity of the particles that instead

the applet would display the average velocity such that the student could

realistically make the calculations.

Re: Problem 8.12.5:

I believe there is something broken in this java applet. The animation implies

that a container is decreasing in volume, yet maintaining a constant pressure

and temperature! This cannot be, so it's not only impossible for the student to

arrive at the same answer, but it can be confusing to students who thought they

understood compression and work, and now they see this animation that breaks

all the rules!

Additional Problem one:

I enjoyed this applet, although it is VERY SLOW to run, and even slower after

making the reccomended changes. Despite the technical difficulties it is a

wonderful illustration of the relationship between pressure and temperature, and

a great reminder for early physics students about the meaning of equilibrium.

Additional Problem Two:

This last applet is instructive, but too difficult to use. The question

concerns a box of O2 molecules, where the individual speeds of the molecules are

given. It wants to know the average speed of all the molecules. I suggest

that instead of having to continuously average the speeds of the 20 molecules

over the course of 20 seconds, the applet be reduced to somthing like 5

molecules. By doing so it makes it feasible that a student could actually

average the speeds and arrive at an answer. Leave the mass computing to the

computers!

13 years ago

### Chris Wolowiec (Student)

It appears as though this Thermodynamics physlet is directed at undergraduate

physics students who have had some education in classical thermodynamics. As an

upper division undergraduate physics student, I found approximately 90 minutes

to be sufficient time to work through the five problems presented in the

tutorial. Most of this time is spent deciphering the mechanics of the user

interface. That is, in answering the questions I found it generally difficult to

determine the spatial parameters required to answer the posed questions.

Problem 2 serves as a good example in illustrating this point: The problem asks

the user to find the ratio of two temperatures (final over initial) for an air

bubble that rises through a tank of water. The air bubble originates at some

distance below the surface of the water at which point an initial temperature

isdefined. The bubble expands in volume as it rises to the surface of the water

where it bursts. The final temperature of the air inside the bubble is defined

at the time immediately before the bubble bursts. In finding the ratio of the

final temperature to the initial temperature the student must recognize that the

gas is essentially ideal and that it undergoes

an expansion between the initial and final states. Some key insight is required

here. The user essentially has two choices for paradigm: isothermal expansion or

adiabatic expansion of an ideal gas. The isothermal expansion may be ruled out

as no heat is added to the gas as it expands and cools. Thus, the user may

decide on an adiabatic expansion paradigm and exploit the proper equations that

follow from the first law and the ideal gas approximation; namely that

(pressure)* (volume raised to the ratio of heat capacities) equals some

constant. From this relationship one may then express the ratio of temperatures

as a ratio of the respective pressure volume products at both the initial and

final states.This is where determining the proper

physical parameters becomes a little problematic. Namely, the user must

determine the initial and final volumes of the bubble. The volume of a sphere is

determined by its radius and so the user must somehow find the radius of the

bubble at both states. This is possible if the user places the cursor at various

points on the bubble to get the best

estimate. This might not seem too tricky except that there are no suggestions or

comments as to how to navigate through the animation. Some helpful comments

might be in order that would facilitate this process so as to allow the user to

spend less time on deciphering the interface and more time on the physics. This

may be taken as a matter of opinion as one might argue that part of the problem

solving here is figuring out how to get the information needed.

On this note, I'll comment that the other problems are less cryptic in that any

physical parameters or variables are much more easily determined. Problem 1, for

example, only requires the user to determine expansion distances for several

metal bars heated over some common time interval. These distances are easily

determined as the metal bars are superimposed over a grid calibrated in

centimeters. Thus, the user may easily draw some conclusion about the material

composition of the metal bars based on the average rates of thermal expansion

over some common time interval.

Problem 3 is a rather straightforward multiple choice question. The user is

presented with three different containers of gas. Of the three containers the

user is asked to select the container of gas particles that most closely

approximates the ideal gas. The particles vary in size and number from container

to container. All that?s required to answer this question correctly is a

working knowledge of what conditions are necessary for a gas to be considered

ideal.

Problem 4 is another working knowledge type question that doesn ?t require any

calculations. The user is presented with graphics of four different types of

gas particles inside of a single container. The particles differ with respect to

mass. Adjacent to the container is a plot of each type of particles kinetic

energy vs. Time. The user then is asked to determine which of the particles has

the greatest average translational kinetic energy. The plot of kinetic energy

vs. Time, however is not really required to answer this question. If the user

remembers that average translational kinetic energy of a gas particle in a

container is proportional to temperature only and not mass, then he may arrive

at the correct answer. This particular presentation is a good example of a

problem that tests a users understanding of one of the more important

consequences of the kinetic theory of gases. In short it asks more of the

user?s understanding of physics and less of his ability to decipher the

interface.

Problem 5 is a bit more difficult than Problems 1,3, and 4. It requires some

calculations, specifically the use of integral calculus. The problem presents a

rather textbook isothermal compression of a gas. The graphics display a mass

on top of a piston. The user initiates the experiment and watches the piston do

work on the gas as the mass falls downward due to the force of gravity.

Throughout the experiment the user will notice thermometer measuring the

internal temperature of the gas to the left of the piston. It?s easy to see that

the temperature of the gas remains constant throughout the compression. Once

the user has determined the process is isothermal he may then find the work of

the gas by integrating the expression P*dV from the initial to final volumes. If

the user assumes the gas to be ideal he may find an expression for the pressure

in terms of volume from the ideal gas equation. Again some effort is needed in

deciphering the graphics in determining the these volumes but not as much as in

Problem 2.

In conclusion, this physlet might be best characterized as abrief homework

assignment testing the users understanding of the more basic concepts in

classical thermodynamics. Improvements could be made in the areas clarity in the

statement of the problems and graphics. In the area of graphics, it should be

mentioned that if the problem requires some insight into how to manipulate the

interface so as to acquire any necessary data/information, there should be some

suggestions as to how to get started. I think this can be done without giving

the problem away.

physics students who have had some education in classical thermodynamics. As an

upper division undergraduate physics student, I found approximately 90 minutes

to be sufficient time to work through the five problems presented in the

tutorial. Most of this time is spent deciphering the mechanics of the user

interface. That is, in answering the questions I found it generally difficult to

determine the spatial parameters required to answer the posed questions.

Problem 2 serves as a good example in illustrating this point: The problem asks

the user to find the ratio of two temperatures (final over initial) for an air

bubble that rises through a tank of water. The air bubble originates at some

distance below the surface of the water at which point an initial temperature

isdefined. The bubble expands in volume as it rises to the surface of the water

where it bursts. The final temperature of the air inside the bubble is defined

at the time immediately before the bubble bursts. In finding the ratio of the

final temperature to the initial temperature the student must recognize that the

gas is essentially ideal and that it undergoes

an expansion between the initial and final states. Some key insight is required

here. The user essentially has two choices for paradigm: isothermal expansion or

adiabatic expansion of an ideal gas. The isothermal expansion may be ruled out

as no heat is added to the gas as it expands and cools. Thus, the user may

decide on an adiabatic expansion paradigm and exploit the proper equations that

follow from the first law and the ideal gas approximation; namely that

(pressure)* (volume raised to the ratio of heat capacities) equals some

constant. From this relationship one may then express the ratio of temperatures

as a ratio of the respective pressure volume products at both the initial and

final states.This is where determining the proper

physical parameters becomes a little problematic. Namely, the user must

determine the initial and final volumes of the bubble. The volume of a sphere is

determined by its radius and so the user must somehow find the radius of the

bubble at both states. This is possible if the user places the cursor at various

points on the bubble to get the best

estimate. This might not seem too tricky except that there are no suggestions or

comments as to how to navigate through the animation. Some helpful comments

might be in order that would facilitate this process so as to allow the user to

spend less time on deciphering the interface and more time on the physics. This

may be taken as a matter of opinion as one might argue that part of the problem

solving here is figuring out how to get the information needed.

On this note, I'll comment that the other problems are less cryptic in that any

physical parameters or variables are much more easily determined. Problem 1, for

example, only requires the user to determine expansion distances for several

metal bars heated over some common time interval. These distances are easily

determined as the metal bars are superimposed over a grid calibrated in

centimeters. Thus, the user may easily draw some conclusion about the material

composition of the metal bars based on the average rates of thermal expansion

over some common time interval.

Problem 3 is a rather straightforward multiple choice question. The user is

presented with three different containers of gas. Of the three containers the

user is asked to select the container of gas particles that most closely

approximates the ideal gas. The particles vary in size and number from container

to container. All that?s required to answer this question correctly is a

working knowledge of what conditions are necessary for a gas to be considered

ideal.

Problem 4 is another working knowledge type question that doesn ?t require any

calculations. The user is presented with graphics of four different types of

gas particles inside of a single container. The particles differ with respect to

mass. Adjacent to the container is a plot of each type of particles kinetic

energy vs. Time. The user then is asked to determine which of the particles has

the greatest average translational kinetic energy. The plot of kinetic energy

vs. Time, however is not really required to answer this question. If the user

remembers that average translational kinetic energy of a gas particle in a

container is proportional to temperature only and not mass, then he may arrive

at the correct answer. This particular presentation is a good example of a

problem that tests a users understanding of one of the more important

consequences of the kinetic theory of gases. In short it asks more of the

user?s understanding of physics and less of his ability to decipher the

interface.

Problem 5 is a bit more difficult than Problems 1,3, and 4. It requires some

calculations, specifically the use of integral calculus. The problem presents a

rather textbook isothermal compression of a gas. The graphics display a mass

on top of a piston. The user initiates the experiment and watches the piston do

work on the gas as the mass falls downward due to the force of gravity.

Throughout the experiment the user will notice thermometer measuring the

internal temperature of the gas to the left of the piston. It?s easy to see that

the temperature of the gas remains constant throughout the compression. Once

the user has determined the process is isothermal he may then find the work of

the gas by integrating the expression P*dV from the initial to final volumes. If

the user assumes the gas to be ideal he may find an expression for the pressure

in terms of volume from the ideal gas equation. Again some effort is needed in

deciphering the graphics in determining the these volumes but not as much as in

Problem 2.

In conclusion, this physlet might be best characterized as abrief homework

assignment testing the users understanding of the more basic concepts in

classical thermodynamics. Improvements could be made in the areas clarity in the

statement of the problems and graphics. In the area of graphics, it should be

mentioned that if the problem requires some insight into how to manipulate the

interface so as to acquire any necessary data/information, there should be some

suggestions as to how to get started. I think this can be done without giving

the problem away.

13 years ago

### Donald Hornback (Student)

The material covered by this review are the problems 8.12.1 through 8.12.5 and

the two additional problems. I spent a couple of hours going though the

problems and my own books trying to figure them out. My overall response to the

physlets offered at this sight is lukewarm. The goal of providing an

interesting, interactive approach to physics is a worthy one; however, these

physlets sometimes fall short. The descriptions (setup) for the problems could

be improved by offering better framing assumptions for the situation. The

illustrations themselves are not as clear as they could be; embarrassingly, it

took me more than a few minutes to realize that that ?thing? in problem 8.12.4

is a pressure gauge. The potential for effective learning through these

physlets does exist, but I feel that the choice of problems and animations could

be improved upon.

The very first physlet, 8.12.1, explores thermal expansion of solid rods, the

point of which is to show that for rods of equal initial length an equivalent

change in temperature will result in an equivalent change in length. This

physlet was fine, though I would suggest making it more apparent or readily seen

that the change in lengths actually is equivalent, such as posting the position

change, perhaps as done in problem 8.12.2.

Physlet 8.12.2 gave me the most trouble of the lot. Assuming that we are to use

the ideal gas equation, I didn?t get their answer after playing with it for a

while. The idea for this physlet is a good one though.

Physlet 8.12.3 offers a brief and VERY qualitative view of kinetic theory and

does not offer anything beyond a similar textbook picture of the three

containers.

Physlet 8.12.4 is an uninteresting trick question, and it failed to illuminate

or illustrate for myself the equipartition theorem in a useful way. Should an

underlying assumption (if it be true) that the system is in thermal equilibrium

be stated for the reader? And if we are to use kinetic theory in the reasoning

for this physlet, does it seem in order based on the image of the container

shown?

Physlet 8.12.5 the container contains a gas (missing assumption: an ideal gas)

that has work done on it in a straightforward isobaric process.

Additional problem one. Again, I had some trouble with the interface, but

eventually I got it to work a bit, though I could not get the particles and

temperatures to do what the physlet says it can do. Increasing the running time

beyond 15 seconds would allow for changes to actually reach equilibrium and

make the physlet more interesting.

Additional problem two. Once I assumed that the units of temperature were

Kelvin, I arrived at the same answer employing a simple plug-and-chug from a

given formula. The interactive aspect of this problem is negligible. My

question is: how is this problem (and several of the others) any different than

problems found in any general physics textbook?

the two additional problems. I spent a couple of hours going though the

problems and my own books trying to figure them out. My overall response to the

physlets offered at this sight is lukewarm. The goal of providing an

interesting, interactive approach to physics is a worthy one; however, these

physlets sometimes fall short. The descriptions (setup) for the problems could

be improved by offering better framing assumptions for the situation. The

illustrations themselves are not as clear as they could be; embarrassingly, it

took me more than a few minutes to realize that that ?thing? in problem 8.12.4

is a pressure gauge. The potential for effective learning through these

physlets does exist, but I feel that the choice of problems and animations could

be improved upon.

The very first physlet, 8.12.1, explores thermal expansion of solid rods, the

point of which is to show that for rods of equal initial length an equivalent

change in temperature will result in an equivalent change in length. This

physlet was fine, though I would suggest making it more apparent or readily seen

that the change in lengths actually is equivalent, such as posting the position

change, perhaps as done in problem 8.12.2.

Physlet 8.12.2 gave me the most trouble of the lot. Assuming that we are to use

the ideal gas equation, I didn?t get their answer after playing with it for a

while. The idea for this physlet is a good one though.

Physlet 8.12.3 offers a brief and VERY qualitative view of kinetic theory and

does not offer anything beyond a similar textbook picture of the three

containers.

Physlet 8.12.4 is an uninteresting trick question, and it failed to illuminate

or illustrate for myself the equipartition theorem in a useful way. Should an

underlying assumption (if it be true) that the system is in thermal equilibrium

be stated for the reader? And if we are to use kinetic theory in the reasoning

for this physlet, does it seem in order based on the image of the container

shown?

Physlet 8.12.5 the container contains a gas (missing assumption: an ideal gas)

that has work done on it in a straightforward isobaric process.

Additional problem one. Again, I had some trouble with the interface, but

eventually I got it to work a bit, though I could not get the particles and

temperatures to do what the physlet says it can do. Increasing the running time

beyond 15 seconds would allow for changes to actually reach equilibrium and

make the physlet more interesting.

Additional problem two. Once I assumed that the units of temperature were

Kelvin, I arrived at the same answer employing a simple plug-and-chug from a

given formula. The interactive aspect of this problem is negligible. My

question is: how is this problem (and several of the others) any different than

problems found in any general physics textbook?

13 years ago

### Lawrence Sweet (Student)

[8.12.1]:

The applet demonstrated how a material expands with four different heat

functions. The graphic demonstration is not really necessary--it takes less time

and energy to visualize different rates of expansion than it does to wait for

the applet to load on campus dual OS machines.

[8.12.2]:

An excellent graphical demonstration of a sperical rising gas region. With the

data provided in the applet one can get started forming a model that provides a

solution technique. One thing left out, however, is a description of what the

fuzzy region around the gas sphere is and how it's effects are (possibly)

neglected in the model.

[8.12.3]:

This animation of different kinematic gas models would be very illuminating to

one not familiar with the assumptions of the ideal gas law. The animations made

it apparent (well, we knew what was coming beforehand actually!) that the

correct model requires intermolecular spacing such that the molecules can be

considered non-interacting. It ran well on challenged hardware.

[8.12.4]:

Quite an amazing simulation. A great demonstration about how mass is a factor in

the concept of kinetic energy. But, there needs to be a way to easily extract

data from the real time graph to work with the problem.

[8.12.5]:

This applet appears to have a serious error in that the pressure does not change

in the animation as the volume drops and the temperature remains fixed.

Additional Problems:

1:

A good applet to visualize the problem posed. All the extra numbers on the graph

are not needed, however.

2:

Extremely slow running but very good applet that shows real time statistical

kinetics and how average molecular speed can be found from seemingly random

motion in a container.

The applet demonstrated how a material expands with four different heat

functions. The graphic demonstration is not really necessary--it takes less time

and energy to visualize different rates of expansion than it does to wait for

the applet to load on campus dual OS machines.

[8.12.2]:

An excellent graphical demonstration of a sperical rising gas region. With the

data provided in the applet one can get started forming a model that provides a

solution technique. One thing left out, however, is a description of what the

fuzzy region around the gas sphere is and how it's effects are (possibly)

neglected in the model.

[8.12.3]:

This animation of different kinematic gas models would be very illuminating to

one not familiar with the assumptions of the ideal gas law. The animations made

it apparent (well, we knew what was coming beforehand actually!) that the

correct model requires intermolecular spacing such that the molecules can be

considered non-interacting. It ran well on challenged hardware.

[8.12.4]:

Quite an amazing simulation. A great demonstration about how mass is a factor in

the concept of kinetic energy. But, there needs to be a way to easily extract

data from the real time graph to work with the problem.

[8.12.5]:

This applet appears to have a serious error in that the pressure does not change

in the animation as the volume drops and the temperature remains fixed.

Additional Problems:

1:

A good applet to visualize the problem posed. All the extra numbers on the graph

are not needed, however.

2:

Extremely slow running but very good applet that shows real time statistical

kinetics and how average molecular speed can be found from seemingly random

motion in a container.