Algodoo

Harris - Maybe I or someone else could help you with with your experiment if you run into problems. Just ask questions. It's the best way to learn!

What are you attempting to do in this experiment?

making balls trying to fly by getting hit by a cog

BTW, how to make a rainbow circle with no texture?

Here is how you can improve your scene. First of all, delete the green plane because it's not needed and only gets in the way.

Next, right click on the axle and hover your cursor on "axles" in the list that shows up. Then click on the motor check box to select it. Then click on "Reversed". Then click on the motor speed box where you see the motor speed value and change it to 5000. Then click on the motor torque and set the value to 5000.

Now, if you successfully did all that, when you Run the scene, the cog will launch all the balls into outer space!

Concerning a rainbow circle without texture, you can possibly do it by shining a laser on the circle, but it would be much easier if you use a texture.

How to make a Rainbow ball:
Rightclick the circle,
Look at the Scriptmenu
go to PostStep
inside the (e)=>{...} write: colorhsva=colorhsva + [0.5,0,0,0];

Voila, a rainbow ball

That's a great idea, FRA32, but it doesn't really produce a "rainbow". It produces slowly changing colors, but that may be acceptable for his scene.