Rolling down a Curve

[Refath Bari]

Hi, I'm trying to make a program where the user can

1. Make two points
2. Draw a curve between the points
3. Have a ball roll down the curve drawn
4. Print the time it took for the ball to roll down from A to B

I've completed #1 and #2. However, to have my ball roll down the curve drawn by the user, I think I need to access the points in the "trail" of the yellow marker. How can I do so? If I can't, is there any other alternative? Thank you for the help. The code is here. 

[Refath Bari]

Update: I've used for i in range (3,len(scene.objects)-1) to create hundreds of little points. I fed those points into a curve, and now an actual curve is generated from the user's drawing. Here's my plan: treat each of the segments of the curve as a cylinder, and then use some Lagrangian Mechanics to simulate the motion of the ball down the curve like a bead down a wire. Please let me know what you thin or if there is a better alternative. Thank you. 

[Bruce Sherwood]

Here is a somewhat similar program:

   https://www.glowscript.org/#/user/matterandinteractions/folder/matterandinteractions/program/06-potential-energy-well

You might wish to represent the curve using a curve object rather than a large number of cylinders:

   https://www.glowscript.org/docs/VPythonDocs/curve.html

Bruce

[Refath Bari]

Thank you for your response. Yes, I already have the object as a curve. Now I have a better idea. No need for Lagrangian Mechanics; Just treat each cylinder like an inclined plane with a=gsinø!

[Paul Camp]

I had a similar problem when figuring out some replacements for online classes -- an inclined plane in which the angle gradually changes. My strategy was similar to yours but it had a weird bug -- the cart kept falling through the track. It took a while to find the logic error. When I stepped forward in time, I forgot to rotate the direction of the velocity vector to the new angle. If you're having your program compute the net force, that shouldn't be a problem but if you're trying to do it kinematically, don't do what I did.

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--

Dr. Paul J. Camp

"The beauty of the cosmos derives not only from unity in variety
       but also from variety in unity"
                 -- Umberto Eco
                     The Name of the Rose