from teacher

I have tried your new simulation and found the improvements in visual much better.  I think it is not necessary to change the mouse and elephant.

However, I do note some areas that perhaps need your attention.

1. There was a pause function earlier on but it is missing now? It stops the simulation at the moment of impact.
[color=blue][b]added at instant of |F| > 0.0 N very precise[/b][/color]

2. This is somewhat more serious.  When the simulation is paused in the middle of the collision, the calculations go haywire and the graph shows a blip. I have attached a screen capture of the blip below. I suspect the calculations restart from zero and hence the blip.
[b][color=blue][b] i don't see it as shown, but i made a dt slow down? it should be able to calculate accurately given the smaller dt steps[/b][/color][/b]

3. Is it possible to reduce the length of the arrow for velocity proportionately? I mean when I set it to 3 ms-1, it crosses  over to the other body. The thickness of the arrow is appreciated, but the length is a bit too long. Perhaps it should only reach the other body if the velocity is set to 10 ms-1, and the length decreases proportionately when the value is decreased.
[color=blue][b]done it is even smaller now, about 0.5 times[/b][/color]

Thanks so much for your help!
[color=blue][b]no problem[/b][/color]