got a request from teacher

We are doing a PLC project cum lesson study on E-field using Java simulation as one of the ICT tool, in 3-4 weeks time.

We would like to request for your help to make the following modifications to the EJS:

1. ability to enter values instead of sliding bars.

2. What is the purpose of value of m=2.0?
[color=blue][b]to experience inertia, F = m*a, so F constant, m double, a halved  [/b][/color]

3. ability to show at a point X, the E-field due to charge A, E-field due to charge B and thus the resultant field.
[color=blue][b]added E1 and E2 and E with selectable check-box to show, only when m is selected[/b][/color]

4. if possible (will be most ideal), can show E-field lines due to 3 charges. It appears in 2008 specimen paper.
[color=blue][b]i cannot do this, maybe you can show another applet[/b][/color]

I have attached the .jar file for your reference.

Thank you.