[quote author=Fu-Kwun Hwang link=topic=1083.msg4113#msg4113 date=1239599479]
[quote]Will it be possible to mark a reference at the begining ? To move the whole installation to show that's the same in the right and in the left ? Maybe it'll be better with a sharp object ?[/quote]

Because you ask me to show the same displacement in the right and in the left, [/quote]

In fact I was talking about moving everything (cranks and wires) to show that anywhere you test the experiment, it gives the same result.
But, it's not necessary in fact.

[quote author=Fu-Kwun Hwang link=topic=1083.msg4113#msg4113 date=1239599479]
that is why I add the "show displacement" as option and set it as default.
Now, you want [quote]I'm wondering too if it's possible not to see displacement by default.[/quote]???
I am confused! [/quote]

Sorry. I'm not very precise when speaking english ;o((
I want first to show them the first experiment without anything ...
Then they will ask for trace and protractor to be sure that it's vertical and downwards

They will then go to the second experiment and see that the measure is done in newton (maybe you can suppress the "dy" parameter because they don't know about this writing).

They will see that the more balls they attach, the bigger the weight value is and that the spring is as well going downwards ...

[quote author=Fu-Kwun Hwang link=topic=1083.msg4113#msg4113 date=1239599479]
[quote]But in the first experiment, is it possible to let a trace of the ball after make it goes up (I mean a circle in dot line to see that when we will let it fall, it'll go at the same place) ?
And a moving square to show that the trace is perpendicular to the ground.[/quote]

Could you create a simple drawing show me what you really want, and explain what you want to do/ how you will use it for teaching purpose? Please also indicates where you want to add "protractor"![/quote]

See attached file

[quote author=Fu-Kwun Hwang link=topic=1083.msg4113#msg4113 date=1239599479]
As far as I know, for the name of the tabs:
you will need to download ejs xml source and modify the name of the tab,compile it again  to make it appear.
Change the name of the tab is not supported at this time yet.

OK, I'll try it but which tool should I use to compile ?