Algodoo

I believe it's because the blue gear has to stop briefly for each tooth transition while the yellow gear keeps moving continuously because of the wider spacing between each tooth.

BTW - What does that number 11235813213455 represent next to your "Thanks bai"? Is that some sort of secret code?

random number for each scene there is a "thamks bai"

Okay, but WHY?

Xray - That may be why powering the yellow gear means the blue gear turns slower, however, with my real life model, I can power the blue gear, and the yellow gear, only powered by the blue gear, will turn faster than it.

Also, the "thamks bai x [number]" is my sort of signature on Algobox. Sometimes, the number has meaning, sometimes it has something to do with the scene, sometimes I'm too busy to find a meaningful number and just slap my numpad. It started on one of my milestone scenes, (think my 200th or 300th scene) but at some point I decided to stop counting and just put in a random number. Maybe it's a bit like Minecraft's famous yellow messages on the start screen, if you know what that is.

I'm too old to play Minecraft but I understand what you are saying. I was just curious, and because I am curious, chances are other people are curious too. Therefore, that random number causes the desired effect for you!