Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Gravity graph

  1. Feb 10, 2006 #1


    User Avatar
    Gold Member

    A gravity graph is a kind of art "tool" that lets you draw nice geometric shapes. It has a board the size of a piece of paper that is weighted in the middle, each of the corners is connected to a piece of string and the strings are tied to a small rectangle (paralell to the board) about 1.5 feet from the board. Basiclly it is a board hanging by 4 strings. Then there is a pen that touches the middle of the paper (that is on the board) and it can bob up and down so that it touches the paper even if it's (=the board) moving up and down. Now to draw a shape you just swing the board and as it slows down and stops it draws nice geometrical shapes. For example, if you swing it in a circle you will get a spirle.

    Now I wanted to make something like that on the computer. First of all I have to simulate the swinging. I thought that I'd think of the strings as tense springs, and figure out the sum of the forces on each corner (spring+gravity), Then from those forces I'll check the sum of the forces at a right angle to each of the 3 axises of spin (x,y,z) and from that figure out the angular acceleration of each axis with Fx = Ia. Then I sum all of the forces around the center point to see how much it moves (translates) with F = ma. For every frame I'd callcuate the rotation by the angular acceleration and the position by the linear acceleration.

    Is this correct? The main problem that I see is that the same forces both spin and move, should the forces that I use to translate be weakened because of the force that is being used to spin? Or is there an easier way to do the whole thing?

  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted