Re: Interactive Physics

[John Mallinckrodt <ajmallinckro@CSUPomona.Edu>]

On Mon, 29 Jul 1996, Slutskin - Shelli wrote:

> For all you folks who have experience with the software program 
> Interactive Physics, Version 2.5:
> Is there a simple way to measure the angle of an incline of a ramp or 
> does it have to be calculated independently using trigonometry?

Shelli,

If you make your ramp by rotating a horizontally elongated rectangle, the 
"phi" field of the "Properties" floating window will contain a value that 
gives the current angle of the incline, although it may take a little 
massaging to put that number in the form you really want.

You can *monitor* the angle by selecting the rectangle and choosing 
"Rotation Graph" from the "Position" submenu under "Measure."  

You can also create a *control* for the angle by selecting the object and 
choosing "Initial phi position" from the "New Control" submenu under 
"Define."  Then you can make everything work in degrees by doctoring the 
entry in the "Properties" window for the rectangle to read 

   "Input[(whatever it says; don't change this!)]*Pi()/180"

and the "Properties" window for the control so that the range is 0 to 90.

The only problem with all of this is that you will have some even 
trickier programming to do if you want a block to automatically start off 
in contact with the incline regardless of its angle.

Good luck,

John
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