# NTNUJAVA Virtual Physics LaboratoryEnjoy the fun of physics with simulations! Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/

## Information about this web site => Request for physics Simulations => Topic started by: jpm1999 on May 29, 2013, 08:55:11 pm

 Title: Request: Horizontal Spring Launcher Post by: jpm1999 on May 29, 2013, 08:55:11 pm I have been looking into 'Modeling Instruction' as a way to teach students conservation of energy in a more conceptual way.  To this end, I would like to start with a simulation/applet that shows a spring launcher and the exchange of energy between elastic, kinetic, and thermal using pie and bar graphs.  The students would first develop their own pie/bar charts after observation of the simulation and then have them verified.  I've attached a better explanation of what I mean. Title: Re: Request: Horizontal Spring Launcher Post by: Fu-Kwun Hwang on May 31, 2013, 03:37:34 pm Let me create one at a time.The first one.You can drag the object to move it from equilibrium position. Use slider to change spring constant, mass or friction coefficient mu.Check bar to show bar chart. Pie chart will be added later.Let me know what need to be changed.Click the following image to view simulation.[eye][ejsapplet][/eye] Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on May 31, 2013, 07:01:21 pm The spring only needs to be compressed and does not oscillate.  It should begin in the compressed position (for simplest scenario).  When the spring is released, the object is launched and moves along a horizontal surface where it is slowed by the friction of the surface.  Changing the spring constant or mass amount should be accompanied by a visual change (size?) in the spring and mass.  Changing the friction of the surface should also be shown by a visual change in the attributes of the surface and the distance the object moves.A pinball machine or gun loader mechanism comes to mind.  Most of the scenarios involve the stored elastic energy of the spring being compared to the resulting kinetic and thermal energy of the object.  Title: Re: Request: Horizontal Spring Launcher Post by: Fu-Kwun Hwang on June 01, 2013, 06:41:27 am I modified the code and it is updated.You can drag the object to move it away from equilibrium position. Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 01, 2013, 06:51:07 am The point is to have the block be launched by the spring and not stay attached.  The kinetic energy it receives from the spring is seen from the motion of the block after it is released and then slowed by friction.  The main action takes place after being launched by the spring.    Title: Re: Request: Horizontal Spring Launcher version 2 Post by: Fu-Kwun Hwang on June 01, 2013, 07:43:34 am Now, I see what you mean.Here is another version.Drag velocity arrow to change it's initial velocity.Click init to reset to initial state.Click the following image to view simulation.[eye][ejsapplet][/eye] Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 01, 2013, 07:50:51 am I don't see that the block actually leaves the spring unless I'm looking at the wrong sim.  It seems to remain attached and oscillate back and forth with the spring.  Vectors will not have been introduced to the students at this point so it is better they are left off.  Title: Re: Request: Horizontal Spring Launcher Post by: Fu-Kwun Hwang on June 01, 2013, 02:05:05 pm I am sorry that the new version was not unload correctly.It is working now. Please check out new version from my previous message. Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 01, 2013, 09:48:31 pm I see that the block is now detached but it needs to start up against the spring with the spring already compressed.  The block should be against the spring ready to be launched to the right.  The vector arrow should be removed or shown pointing to the right after launch.  When there is no friction, the block should continue off the page and disappear.The area after the spring should be much larger since that is where the action is taking place.I've attached a better picture of what I mean. Title: Re: Request: Horizontal Spring Launcher version 3 Post by: Fu-Kwun Hwang on June 03, 2013, 03:39:23 pm Drag the block to the left (compress the spring) and let go. Click the following image to view simulation.[eye][ejsapplet][/eye] Title: Re: Request: Horizontal Spring Launcher version 3 Post by: Fu-Kwun Hwang on June 03, 2013, 08:36:50 pm I tried to create another version.Drag the block to the right (compress the spring) then release it.Click Bar checkbox to show bar chart.Click the following image to show the new version.[eye][ejsapplet][/eye] Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 03, 2013, 11:56:54 pm YES!  The friction and spring constant sliders could use a bit of fine tuning but, it's much more like what I was looking for.  Also, it would be great to be able to measure/change the height of the ramp.Thank you. Title: Re: Request: Horizontal Spring Launcher Post by: Fu-Kwun Hwang on June 04, 2013, 06:04:28 am I just modified the code and it is updated (you can drag the object to the left at different height now). Let me know what you would like the slider for spring constant to be changed. Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 05, 2013, 03:11:17 am Cool!  It's reversable!  I put block on the ramp to release it and it compressed the spring. It is useful as it is right now.  Having actual numbers for calculations is an extension of what I'm trying to accomplish - conceptual understanding with bar and pie charts.  I may use numbers in a later lesson but the concepts are first and foremost.Being able to adjust the mass even if it is for one other setting would be helpful.Hmmm.  I don't know about numbers for spring constant or friction as much as what I want it to do.  I'm having trouble explaining it.I would like to see 2-3 settings for the spring constant but it must also make sense when friction is added as to where the block goes (height up the ramp or not) as a whole.First, when no friction is present, the block should return to the same height on the ramp as it oscillates at a particular spring setting.  If the spring provides the most energy possible, it should go the highest on the ramp.  If there is less energy provided by the spring, it should oscillate at a lower position on the ramp.  The rest is a combination of spring and friction settings as long as they make physical sense.Ex:  With Friction/Spring ConstantBlock should not go as high up the ramp with friction as it does without friction for the same spring setting.One setting - block halfway up rampAnother setting - block doesn't reach rampThere could be another setting where the block makes it part way up ramp when it is without friction (spring constant setting) and doesn't make it up ramp when friction is present.I need to think about how to describe this better. Thanks for helping me. Title: Re: Request: Horizontal Spring Launcher version 5 Post by: Fu-Kwun Hwang on June 05, 2013, 08:20:57 am QuoteHaving actual numbers for calculations is an extension of what I'm trying to accomplish Do you mean user can input number to change spring constant, mass,friction coefficient, etc?Quotewhen no friction is present, the block should return to the same height on the ramp as it oscillates at a particular spring setting. The previous version should be able to show that:  the block did return to the same height on the ramp when no friction is present.QuoteBlock should not go as high up the ramp with friction as it does without friction for the same spring setting.I just create another version: Try to let the block oscillate without friction, then adjust friction coefficient. The block will slow down due to friction.Another block will show up -- which move for frictionless case.I hope this will be close to what you need.Right now. Friction can be added when it move on the horizontal track.There is no friction when the block is moving on the ramp.Do you want to add friction between the block and the ramp?Click the following image to show the new version.[eye][ejsapplet][/eye] Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 06, 2013, 05:15:53 am Maybe I should take it a step at a time to collect my thoughts:Let's leave out number considerations and vector indicators.I think the previous version works better.  It did show the block returning to the same height on the ramp when no friction was present.  I also liked that the block went as far up the ramp as possible with a high spring constant.  What I would like to see is for it go to a different (lower) position on the ramp if the spring constant is decreased (also without friction).  These two setting for the spring would be enough to show the difference I am looking for.It's ok that the ramp doesn't have friction.  I'll work on the ideas for friction and mass next.  I hope I'm not being too frustrating for you.Jo Title: Re: Request: Horizontal Spring Launcher Post by: Fu-Kwun Hwang on June 06, 2013, 02:38:47 pm Quote from: jpm1999 on June 06, 2013, 05:15:53 am  What I would like to see is for it go to a different (lower) position on the ramp if the spring constant is decreased (also without friction).  These two setting for the spring would be enough to show the difference I am looking for.The total energy should be conserver if there is no friction.Which means that it should always go to the same height even the spring constsnt was modified by user. (It is the maximum compression of the spring will be changed.) May be I mis-understood what you mean. Please explain it in more detail. Quote  I hope I'm not being too frustrating for you.No problem.  I hope the simulatin created is really what you need for your teaching. :D Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 07, 2013, 05:07:51 am I don't know how to get the previous version back.  I think it was closer to the idea than the current version.I've included snapshots of what I meant.Set up 1:  At the highest 'k', the block rises to the highest point on the ramp (no friction).Set up 2:  At a different setting for 'k', the block rises to a different point on the ramp but not the highest (no friction).These two setting can be the basis of the design.   Title: Re: Request: Horizontal Spring Launcher Post by: Fu-Kwun Hwang on June 08, 2013, 08:48:09 am There are 5 different version available: at message 2,6,10,11,15You might want to check out message for previous version. QuoteSet up 1:  At the highest 'k', the block rises to the highest point on the ramp (no friction).Set up 2:  At a different setting for 'k', the block rises to a different point on the ramp but not the highest (no friction).The highes point on the ramp is determined by the total energy of the system.   The assumption for the above two settings is the block were compressed at the same displacement initially(before released).Once the block is released, the highest point on the ramp is not dependent on spring constant k.$mgh= \frac{1}{2}k x^2$ , so $h=\frac{1}{2mg} k x^2$ Your setup 1 need one more condition: what is the displacement (x) of the spring. Do you want me to add another slider for the displacement? (so that you can fix displacement while changing spring constant k ?) Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 09, 2013, 09:44:32 am QuoteThere are 5 different version available: at message 2,6,10,11,15I think version 10 or 11 is the one I was referring to that worked best (except the vector has to be removed)QuoteThe highest point on the ramp is determined by the total energy of the system. This is exactly what I want to show. QuoteThe assumption for the above two settings is the block were compressed at the same displacement initially(before released).Once the block is released, the highest point on the ramp is not dependent on spring constant k.I realize the height on the ramp doesn't depend on the spring constant directly.  But, help me understand:  If there were two springs - each with the same displacement (x), wouldn't there be a difference in the stored elastic energy depending on the spring constant?  Wouldn't it then translate to different heights on the ramp (conservation of energy)?     My interest is in demonstrating conservation of energy by varying the energy in the spring to achieve different heights up the ramp - 2 settings.  The same spring (k) could provide both settings if the displacement is varied (since it is the squared value).  So, either having 2 settings for the constant (k) or 2 settings for the displacement (x) would work.  I would rather not have both because I want to make it visually uncomplicated and because I would like to add friction to both settings eventually.          Title: Re: Request: Horizontal Spring Launcher version 6 Post by: Fu-Kwun Hwang on June 09, 2013, 08:38:54 pm I hope the following version is what you want.You can select either "Fix k, change dx" mode or "Fix dx, change k" mode.For Fix k, change dx mode:You can drag dx slider when the simulation is paused.For Fix dx, change k mode:You can change dx only by dragging block.You can click "init" to change the displacement of spring to previous value.The block will move to different heights up the ramp with different spring constant.I also add numerical value for kinetic energy, potential energy, etc. [eye][ejsapplet][/eye] Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 09, 2013, 08:58:49 pm I don't see the jar file.  It seems we've gone in the opposite direction from a visually intuitive sim.  Is there anyway to get rid of the sliders completely and just have two settings for the spring displacement by compressing it more or less? Title: Re: Request: Horizontal Spring Launcher Post by: Fu-Kwun Hwang on June 10, 2013, 08:09:35 am I am sorry that I forgot to check the uploaded file.It is uploaded again! Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 11, 2013, 01:56:18 am Yes, it's there now.I used the fix k, change dx.  For the highest dx, it should go as high up the ramp as possible.  And, for another setting of dx, it should go part way up the ramp (half?).  Could the path indicator (line) be removed? Title: Re: Request: Horizontal Spring Launcher version 7 Post by: Fu-Kwun Hwang on June 11, 2013, 11:24:27 am Here is the new version . Trace has been removed.It will go as high up the ramp as possible when dx slider were dragged to the largest value.It could be an exercise for student to find out what should be the value for dx slider for the block to go half way up the ramp (turn on the bar chart will help).Click the following image to show the new version.[eye][ejsapplet][/eye] Title: Re: Request: Horizontal Spring Launcher version 7 Post by: lookang on June 12, 2013, 08:56:31 pm Quote from: Fu-Kwun Hwang on June 11, 2013, 11:24:27 amHere is the new version . Trace has been removed.It will go as high up the ramp as possible when dx slider were dragged to the largest value.It could be an exercise for student to find out what should be the value for dx slider for the block to go half way up the ramp (turn on the bar chart will help).Click the following image to show the new version.[eye][ejsapplet][/eye]ejsuser/2/ejs_springincline4.jar not foundneed to upload again?:) Title: Re: Request: Horizontal Spring Launcher Post by: Fu-Kwun Hwang on June 13, 2013, 06:11:11 pm Thank you! It is uploaded again.  ;D Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 17, 2013, 10:48:19 pm Sorry, I was away for a while.The applet works great!  Is it possible to have a different bar graph for the potential energies (spring and gravitational)? Title: Re: Request: Horizontal Spring Launcher Post by: Fu-Kwun Hwang on June 22, 2013, 10:36:38 pm I hope the following is what you want.Click the following image to show the new version.[eye][ejsapplet][/eye] Title: Re: Request: Horizontal Spring Launcher Post by: jpm1999 on June 23, 2013, 01:04:49 am Yes!  It's perfect.  Thank you so very much for all your hard work.Jo