EJSS wave 1d superposition model

The EJSS wave 1d superposition model  shows how the superposition principle gives rise to wave phenomena such as standing waves and beats. Users enter real-valued wave functions and dropdown menu for ease of inputs  and observe both the time dependent functions and their superposition. This model uses the JavaScript mathematical function parser.
       A wave is a disturbance, such as sound, that propagates through space. For a wave propagating in one dimension, we use a wave function u(x,t) to represent the wave at position x and time t as shown in the screen shot.  Although a sinusoidal wave function is a very common type type of disturbance, we should remember that there are many other wave functions, such as shock waves, that do not fit this functional form.  

The EJSS wave 1d superposition model  was developed using the Easy Java Simulations (EJS) version 5. It is distributed as a ready-to-run html page and requires only a browser with JavaScript support.

The mathematical equation used are:

 f(x,t)=sin(πx−t)

 g(x,t)=sin(πx+t)

which the resultant is 

 u(x,t)=sin(πx−t)+sin(πx+t)

the dropdown menu has some function typical in the A level Physics

 f(x,t)=sin(πx−t)

 f(x,t)=12sin(πx−t)

 f(x,t)=2sin(πx−t)

 f(x,t)=12sin(πx−t)

 f(x,t)=2sin(πx−t)

 f(x,t)=sin(πx−12t)

 f(x,t)=sin(πx−2t)

 f(x,t)=sin(πx−t−π2)

["sin(pi*x-t)","0.5*sin(pi*x-t)","2*sin(pi*x-t)","sin(0.5*pi*x-t)","sin(2*pi*x-t)","sin(pi*x-0.5*t)","sin(pi*x-2*t)","sin(pi*x-t-0.785)","sin(pi*x-t-1.57)"]

["sin(pi*x+t)","0.5*sin(pi*x+t)","2*sin(pi*x+t)","sin(0.5*pi*x+t)","sin(2*pi*x+t)","sin(pi*x+0.5*t)","sin(pi*x+2*t)","sin(pi*x-t+0.785)","sin(pi*x-t+1.57)"]

 f(x,t)+g(x,t)=u(x,t) 

1. recreate on a fresh ejss using codes from http://www.compadre.org/osp/items/detail.cfm?ID=13014
2. use design ideas from http://weelookang.blogspot.com/2010/06/open-source-ejs-superposition-of-2.html
3. fix a bug in the input fields need _view._update(); //critical for immediate update

Area of improvement: Done!

1. cannot figure out how to make a dot that travels on the  f(x,t) and  g(x,t)

the generic wave form has an equation of this form: