Ejs open source java applet 1D collision carts Elastic and Inelastic Collision

[lookang]

i managed to meet up with my school teacher friend and got some of the student feedback forms.
i key in the data (43) / ~200 forms, the data seems to suggest it is a meaningful practical lab made possible through this applet and planning from the teachers in that school RVHS.
(63) / ~200 as of 8sept2010




you can see the data (feedback) and come to your own conclusions whether it is meaningful to start using similar applets as practical lessons to give students the chance to conduct inquiry learning in student centered pedagogy.

Google Form which all can see, not edit
https://spreadsheets.google.com/ccc?key=0AjIvSg-TzZrZdGVoQzE5WlVWcU9FREJhaXBLYi1jZ1E&hl=en&pli=1

summary of results
https://spreadsheets.google.com/gform?key=0AjIvSg-TzZrZdGVoQzE5WlVWcU9FREJhaXBLYi1jZ1E&hl=en&pli=1&gridId=0#chart

[lookang]

Grouping of would you want to attempt similar lessons for other topics in the future?

+ 37/43 plus points 86%
it is very interactive
dry to learn from lecture, need experience to understand
i would love to attend such lessons because it involves a higher degree of interaction between user and computer
it is interesting
help visualize and learn about the concepts
fun and interactive and can discuss with partners
easier to understand
simulation let us visualize the events and the hands-on activity boost interest
easier to understand with demo and actual calculations
more interesting way of learning allow us to enjoy learning
more enjoyable than normal lesson, due to the interactivity
interactive and effective in teaching concepts
keeps me awake and alert to pay attention to topic taught
enables us to do collaboration discussion
more interesting and enjoyable than lectures
less passive learning
such lessons promote collaborative learning
promote collaborative learning
challenged to make connections, when we do there is a great sense of satisfaction
very interesting
easier to learn about relationship between variables
simulation help understand topics, instead if just images on notes
interesting change from usual lesson
takes much less time, view accurately the theoretical outcomes
can watch effect of collisions in different situations
hands on activity more entertaining and will make lesson less dull therefore we can concentrate even better
interesting
these kinds of lesson force us to think critically. it makes us look at the results, analyze and then find the trend within, which is a really good way to learn independently. it also gives us confidence and a sense of accomplishment when the conclusions we arrive at are correct. my favorite
easier to understand than theory lessons
it lets me figure out the concepts rather than just listen and believing what is taught without understanding
the lesson is interesting and hands on
normally people would have to experience any physics concepts themselves through hands on to really remember concepts. Lectures on the other hand may not be effective since maybe what the lecturer is bringing through us is unclear, and thus practical lessons to learn concepts is a great learning deal
allow to explore the knowledge and content ourselves, interesting


- 6/43 negative points 14%
quite hard to learn through thus with the teacher does not teach and explain much about it
benefit more from just watching a clip
instructions are very confusing and even if we get the answers, we do not understand why it is that way
not clear about the learning points
the activity worksheet did not generate much thinking and concept understanding, just simply presents a set of values to copy to get the answers worksheet design issues??
not interesting

[lookang]

is there anything you feel should be done to enhance the lesson?

- applet design issues
add sound effects done! 29May2010 effect of sound after collision http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=824.0
more sound effects added my answer! can't add sound on perfectly elastic due to conservation of energy
program lacks instructions to what to start with. clearer indications and more organized layout is preferred i can change the layout but i need to understand how to improve it, need concrete layout and design diagram, but good point
simply recording of results is rather monotonous. program designed as a game, thereby making it more interactive. done 26May2010 adding the game checker for auto assessment of learning thanks to http://www.compadre.org/osp/items/detail.cfm?ID=10000&S=7 One Dimensional Collision Model written by Andrew Duffy
at the end a table can be provided and it would provide us with the values. from there, we do analysis. let me find out if it can and should be done, great suggestion!


- implementation issues beginning of lesson
short briefing before use applet
instruction should be more clear
explain basic concepts before carrying out activity
crash course in concepts of momentum and relevant calculations
go through basic theory
short introduction to the topic before the experiment, so as to give a better idea of what is going on.
we can also be taught some important points to pay attention to


- implementation issues during lesson
state the assumptions and give questions instead of just completing the table
tabulate less data strain on hands
too many reading to take for the table
give hints to think about what they have done and draw correct conclusions
more explanation for data collected to aid understanding
teacher provide some questions, then discuss in small groups, then discuss as a class.

[lookang]

any other comments from students


instructors are very helpful of course, 2 teachers in one lab plus i am a super teacher
i really thank you for spending time coming up with this program.you are really an educator who cares and dares to try new things. thanks! hope you can come up with even better programs so that they can empower students in physics subject. just wanted to share this joy with Prof Hwang and others educators in this forum, keep doing what you are doing with learning with simulation (technology).

[lookang]

doing an upgrade

[lookang]

another discussion on this simulation

> 1. I have tried the Java sim from your blog, can set velocity to 0.5 but not 0.2, 0.3 etc. Also, it will be better if users can directly type the values they want, instead of dragging the scale.
>
Did u try to key input values in the input fields
I just tried seems 0.2 can be set.
Avoid the sliders for specific values.



> 2. you have a "paused at collide" function which is useful, is it possible to show the forces just as how you display the velocity vectors? Can show students forces acting on block A and B are the same according to NTL. From there, we can develop the concept : force of same magnitudes, same time during collision, Fx t, so change in momentum for block A and B ae the same, but in opposite direction. (I have attached a partially done worksheet, adapted from University of Washington using the inquiry approach)
>
Seems like a good idea

> 3. In relation to pt 2, can we add a Force-time graph?
>
But the force time graph is just a _|_ graph nothing much to see unless we redesign the model to be more like real life then can see a bit _|-|_ graph. Can u show a graph u have in mind ?

> 4. Can we input very large values for mass. e.g. a very small mass collide with a very large mass, just like we bounce a ball on the ground. Conversely, it will be good if we can show very large mass colliding with very small mass.
>
Input field can accept any mass, don't use the slider

> 5. This is probably the hardest pt. Coefficient of restitution, e, is not covered in the syllabus. Students usually use u1, u2 and v1 or v2 to find the other final velocity. They do not need to care about the value of e and do not know how to calculate e anyway. It will be useful to students if we can allow them to input v1 or v2 such that they can check their tutorial answers, but of couse got to ensure that corresponding value for e is also calculated correctly.
>
It is already possible.
Did u select the table check-box to key in values ?

[lookang]

1. Think I will stick to the original Java Sim that RV uses.
Think my worksheet focus on constructing knowledge from NTL, then towards COM.
It should also test students on multiple intelligence and relating the momentum-time and force-time graph. (Please refer to attached pic for graphs)
 
i will try to add http://www.thephysicsfront.org/items/detail.cfm?ID=3969 into the current sim to achieve what u want

2. As for input of values for mass, u1 and u2, I can do it now. thanks.
 
nice


However, don't think i can input v1 or v2. The java sim calculates v1 and v2 together based on a certain value of e.

yes it cannot be done yet, the physics is not deterministic


But students don't know about e, so can we just let them input v1 or v2 and calculate the other, without showing e. (Note: in tutorials, when we give students a certain value of v1, we are already assuming a certain value for e)

here i disagree with the syllabus, the treatment of collision is inadequate to prepare physics students for university.
let me think how to solve this, maybe i release another sims just for v1 n v2 inputs
 
3. For the momentum-time graph, there is a vertical line at t=0. Looks like the momentum dropping from somewhere. Can we eradicate this?

yes, done



hi prof!
can allow file extension .docx ??
Dynamics Wksht_EJS.docx.
You cannot upload that type of file. The only allowed extensions are gif,jpg,mpg,pdf,png,txt,xml,java,html,jar,ip,avi,swf,zip,doc,mov,jpeg,htm,jqz,rar,trk,mp4,ejs,apk.

[lookang]

changes
added F vs t graphs
added if (t>=tcollision&&t<=tcollision+dt){
F1 = mass1*(vx1-vtemp1)/dt;
F2 = mass2*(vx2-vtemp2)/dt;
totalF = F1+F2;
  }
added different way to make sound
if (elastic==true)
{
  sound=false;
}
else
{
Toolkit.getDefaultToolkit().beep();
//sound = true; // sound produced
//t_onsound = t;
}
added pause and diagram of F1 and F2

enjoy!

[lookang]

Question:
u really want a input field for v1 n v2?
that would mean a lot of possibilities,
e >1 super elastic
e=1 ok
0>e>1 ok
e =0 ok
e<0 impossible to happen

what computer responses are required for e>1 and e<0 ?
disallow?
a text message? "super elastic" or "impossible!,
re key v1 n v2"

any thoughts?

i would not be able to add on to the same simulation, i will have to release another version cos the codes need to be reprogrammed with v1 n v2 as inputs

Hi prof hwang!
i am at Radisson Hotel Ontario Airport http://aapt.org/Conferences/wm2012/hotelpage.cfm
2200 East Holt Boulevard
Ontario, California 91761
United States

but notice the forum still capture as 04:26:31 pm » posted from:SINGAPORE,SINGAPORE,SINGAPORE
for your info

[lookang]

discussion with teacher

1. Request to show the final velocity of the carts only after collision. Currently, when I input the initial velocities, the final velocities are shown immediately, even before I click play
 
ok,

2. Request to display magnitude of F1 and F2. Currently, when use "pause" function, vector arrow of F1 and F2 are shown but not its magnitude. Furthermore, the Force vector is often too long and goes out of the screen. Students cannot compare its magnitude.dd

reduce the length
show number now //force
  s_F1 = " { F_1 } = "+double2String(F1,1000.);
  s_F2 = " { F_2 } = "+double2String(F2,1000.);

 
3. Enlarge or zoom in the time of collision. i.e. enlarge the width of the spike in F-t graph.
Rationale: during collision, the force acts on the carts over a period of time. During this time interval, at any instant, the force acting on the two carts must be equal and opposite. Wants to emphasize this pt to the students.

cannot be done, because of the very short time during collision happens only of a small fraction of dt.
can zoom in but the period of time is a small fraction of dt thus it draws like a triangle.

 
4. Related to pt 3, since the F-t graph now looks like a triangle, the force during collision is not constant. As such, the momentum-time graph must show a curve during collision.
 
Force acts for a very very short time, so it cannot be constant, it is a spike value.
so momentum is slope down or up depending on whether it is an decrease or increase of momentum.


5. What is "game"? in the Java Sim. What is the function of this?

game is an assessment of learning, where student can try to key in values to check whether they understood the concepts in COM and COKE during collision.

[lookang]

discussion with teacher

For pt 3 &4, our purpose is to really focus on what happen during the collision. Upon collision, the colliding bodies undergo periods of deformation and then restoration, so the force during collision will not be constant. Nevertheless, at any instant during collision, the forces acting on body 1 and 2 will always be the same. This is a very important concept from NTL that we want to emphasize to students. Moreover, this is similar to the graph in TYS N04/3/2.
 
We hope you can help us change the time scale of the graph, so that we can amplify the time during collision.

For that TYS qns I mentioned, the F-t graph is a curve (which i think might be harder for programming)
I was thinking more of a triangle instead of a curve, and the inverted triangle that is of cos symmetrical. Add more frames/steps during the period of collision? In this case, it will be obvious to the users that any pt in time during the collision, the forces are always equal (one positive, one negative)

if it is a triangle, it is done
it zoom in, select data tool by right click and select the Ft graph

it is a triangle impulse, not a curve impulse, the concepts is still
the same, forces F1 n F2 are equal and opposite act on different
bodies.

the time scale cannot zoom in during collision, because the computer
model currently assumes instant re-bounce (idealistic), really touch
and go, no spring like deformation

to get a wave impulse like in TYS N04/3/2, i need to reprogram the
collision for all cases of collision e=0, 0 < e < 1, e=1 etc. which the
curve impulse is valid for 0 < e < 1, e=1 etc, but not for e=0 i think.
so it is rather complex.

[lookang]

discussion with teacher

We are receptive of triangle impulse. in fact, we agree that the algorithm for curve is too complex.
The two triangles can indeed show F1 equal to F2 at the peaks of the two triangle impulse.
 
Only thing is if the triangle impulse is wider (maybe change the scale of the time-axis etc. ..i don't know...) then at any pt in time inside the triangle, we can show F1 will always be equal to F2. NTL always applies. This is the enduring understanding that we want to instill in our students.

we can get student to do a data analysis of the Ft graph
scale horizontal set to just before and just after the collision
as in my 2 pictures.

get the student to think about
0.60 s
0.601
0.602
0.603
.....

with these evidence data, they could conclude that the F1 = - F2 during collision, thus N1L is validated.

[lookang]

another discussion with another teacher



Is it possible to introduce the following changes to the simulation?
1.  remove the formula

in line with our 2nd multiple representation pedagogy and research, the formula is actually a form of symbolic representation that we speculate helps learners form a coherent mental model of this topic of momentum.
can keep please and use it?
 

2.  remove the hints

same as 1, can keep please and use it?
our research experience using this computer model suggests it could be useful to promote thinking about the problem of types of collision types

3.  can the final velocities appear only after the collision?

i think already done based on earlier request by AJC teacher

4.  remove change in font size

we speculate the size emphasis help learners focus on that is being modeled in that time

5.  a much larger difference in mass? (right now it's only 1 to 7 kg?) possible to key in any positive real number?

key in directly into the input fields, all computer models currently that lookang makes, can have or already has this user input features

6.  same for velocity?  The arrow length can be proportioned between the two velocities?

i believe it already is drawn proportionally and always pointing to the right consistent in convention to traditional pen paper solutions. please check?

7.  spell momentum instead of mom? Can also use p1 and p2 too.

i think can spell momentum, i try but please note the space constraints already inside existing model
i think can use p1 and p2 but it is better than m1*v1 or m1*u1 ?
i normally avoid using p1 as it could be confusing as p1 = m1*u1  when t < tcollision and p1 = m1*v1  when t > tcollision.
please think this through i should be able to but i need you to be sure

[lookang]

another good suggestion by teacher


Good idea, I try no promises, I need to figure out the computational physics of this, in relation to what is already made.

“possible to make "explosion" case?

Before "explosion", one single mass to be keyed in (either moving or stationary)
After "explosion", 2 masses flying apart (students to key in ratio?)
Quantities to be calculated are final velocities, initial and final KE, initial and final momentum.
“

[lookang]

work in progress

[lookang]

more request



The arrow length can be proportioned between the two velocities?
So if i want to key in v1 = 500 m/s, the space constraints wouldn't allow
>> it. So i wrote

done, it saturated








explosion:
>> M before explosion
>> U before explosion
>> Fraction of masses after explosion or m1 and m2
>>
>> To calculate:
>> Initial KE
>> Fraction of Final velocities
>> Fraction of Final KEs
>>
>> Formula:
>> MU = m1v1 + m2v2

not done, not sure if it is can be done

[lookang]

work in progress

teacher discussion.
1. The F-t and momentum-time graphs are not aligned. The end of the momentum change seems to be aligned with peak force
2. The velocity vector is incorrect. For e.g. 1 m/s is longer than 2 m/s.


1. consulting
2 fix bug of arrows and also added Math.abs() to force arrows always to the right

[lookang]

after discussion with teachers

several request were made.


1. velocity convention to be direction left is negative while always showing magnitude to be consistent with this particular schools teaching practice.
done

2. bug fixed for tmax for the graph to show the tmax consistently

3. some text changes as explain by teacher in accordance to text used in A level now.
perfectly elastic == elastic
partial inelastic == inelastic
perfectly inelastic == perfectly inelastic


4. spring model for collision will be release in a different model as i want to keep this version with event handler.
watch out for that

[lookang]

more changes
set x1 = - 0.25
set x2 =  0.25

the spring force collision model need a longer time to saturate to the ideal values.

enjoy!