# If a plane can take off on a conveyer belt, then why not use conveyer belts? **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [March 27, 2018, 3:33pm UTC](https://boards.straightdope.com/t/if-a-plane-can-take-off-on-a-conveyer-belt-then-why-not-use-conveyer-belts/811279 "2018-03-27T15:33:10Z")\ **Posts on this page:** 1\ **Showing post:** 94
**Author:** ![nate](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nate/32/13085_2.png) [@nate](https://boards.straightdope.com/u/nate)\ **Post date:** [March 29, 2018, 9:43pm UTC](https://boards.straightdope.com/t/if-a-plane-can-take-off-on-a-conveyer-belt-then-why-not-use-conveyer-belts/811279/94 "2018-03-29T21:43:05Z")
> [@k9bfriender](#): > > What is causing the wheels to turn? Sounds like you’ve basically just set up a system where everything is locked up, and nothing can move. To simulate the treadmill, where the treadmill speed \> wheel speed, the sun gear (the treadmill in this analogy) will spin using whatever, it doesn’t really matter, but if it helps imagine an electric motor spinning it. This will cause the planet gear to somewhat rotate but mostly revolve around the sun gear. Putting a little force on the axle attached to the planet gear will allow you to move the planet gear around the sun gear regardless of the rotation speed of the sun/planet gears. Placing these gears on a bar that can freely rotate around its center will split any force placed on the planet gear’s axle causing the speed increase to appear on the sun and planet gears nearly simultaneously. I’m trying to find a free physics simulator where I can illustrate this, mainly to make sure I’m not missing something due to a huge blind spot. --- _[View the full topic](https://boards.straightdope.com/t/if-a-plane-can-take-off-on-a-conveyer-belt-then-why-not-use-conveyer-belts/811279)._