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

Information about this web site => Question related to Physics or physics related simulation => Topic started by: ahmedelshfie on December 30, 2009, 05:42:18 pm



Title: Ask : How to draw v(t) with EJS
Post by: ahmedelshfie on December 30, 2009, 05:42:18 pm
Hello professor this project XML my ask is about
graphic of (V) i typing equations Vx,,Vy,,and V
but only graic v about time no work so i change
i think is mathematics on evolution... so (T)(V) graphic no Right .. thanks for help
with my respet
Ahmed


Title: Re: Ask
Post by: Fu-Kwun Hwang on December 31, 2009, 10:54:14 pm
Quote
Hello prof thank you for your help the project is motion project v;vx;vy i get equations vx and vy right valecoty, the ramp and grafity only problem about t(time) grfic of time so variables is,, t = 0.0,, y = 0.0,, vy = 0.0,, g = 9.8,,  x = 0.0,,  vx = 0.0,,  v0 = 10,,  theta = 1.57,,,,
ok and all type is (double) so i make equation in initialization  vx and vy by this way vx = v0*Math.cos(theta); / vy = v0*Math.sin(theta);
and typing in initialization  t = 0;
                                    x =0;
                                    y =0;
                                    g =9.8;
ok so all get right about grafic now only the problem is i wanna get grafic of time and for me get grfaic time on plot that mean i use (V) so
v = math.sqrt(vx*vx)+(vy*vy-g*t); i typing by way of easy java becouse i try typing equation by mathtype and paste for you but no accept  so prossor i hope u can helpĀ“me how i get (V) on program and grfic t (time) for (V)
thank you profssor for you help
with all my respect
ahmed
The above message is what I received in my private message box.
The following is my response to your question.

Code:
t = 0.100;
x = 0;
y = 0;
g =9.8;
vx = v0*Math.cos(theta);
vy = v0*Math.sin(theta)-g*t;
The above is what you wrote in initialize page. Normally, what I will do is
Code:
t=0.s;
x=0;
y=0;
g=-9.8;
vx=v0*Math.cos(theta);
vy=v0*Math.sin(theta);
because you already set up correct evolution relations:
dx/dt=vx
dy/dt=vy;
dvy/dt=-g;
when simulation is playing, it will calculate x(t),y(t),vy(t) according to the above equations.

There are three trace in your plottingPanel:
Code:
The name:  Input X and Input Y are
1. plot : x,y
2. plot2: x,vy
3. plot2: vx,t

If I want to show trace vary as function as time t, the Input X property should be all time t.
If you want to show v=Math.sqrt(vx*vx+vy*vy) as function of time
you can assign Input X as t, and assign Inoput Y as Math.sqrt(vx*vx+vy*vy).
If you assign Input X as t, and Input Y as vy, you will find a stralight line because vy=vy(t=0)-g*t;


Title: Ask/board:29-100-
Post by: ahmedelshfie on January 04, 2010, 04:47:00 pm
Hello profssor this Xml file i post topic befor about this project like you ask me
im try get ghrapic of (V) i think the problem in evolution im wait your answer profssor
with all my respect
Ahmed


Title: hi
Post by: ahmedelshfie on January 04, 2010, 07:09:09 pm
Hello prof i find word file i send you as jpg for you see graphics of velocity with time (V)(T)
thanks so much
Ahmed


Title: Re: hi
Post by: lookang on January 04, 2010, 09:18:11 pm
u want to plot vx , vy and |v| ?

U may want to look into the source xml here
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=745.0




Title: Re: How to draw v(t) with EJS (modified EJS xml file)
Post by: Fu-Kwun Hwang on January 05, 2010, 11:25:25 pm
Hello prof i find word file i send you as jpg for you see graphics of velocity with time (V)(T)
thanks so much
Ahmed

You should move
Code:
if (y< 0) _pause();
to Fixed relations tab.

You do not need $\frac{dv}{dt}=g*t-vy$.
$\frac{dvy}{dt}=-g$ will calculate $vy(t)=vy(t=0)-gt$ for you


I have modified your ejs xml source.
Please check out the attached file.