Hello, I have a question about using the properties of conservation of angular momentum to provide mechanical resistance. Basically, I'd like to create a device that spins a disk similar to a gyroscope. The device has an external input that, depending on the configured orientation of the disk, will spin the disk either in line with its axis of rotation to provide no resistance, or against it to provide resistance. http://i.imgur.com/dfU4REU.png Take the above crappy drawing as a basic example. As the input (at the bottom of the image) turns about, it will turn the disk in such a way that it will provide resistance because of the properties of conservation of angular momentum. To control the amount of resistance the system provides, the disk chassis can be rotated as the arrows on the left of the image demonstrate. If the disk chassis is rotated 90 degrees, the disk would be spinning such that its axis of rotation would be in line with the input of the device, providing no resistance. My questions are first off, does a device like this make sense? More to the point though, I'm wondering what the properties are of conservation of angular momentum, in layman's terms. When providing resistance, will the disk slow it's rotation speed? Is the energy required to keep the disk spinning equal to the resistance it provides? How much resistance can be expected depending on the mass of the disk? Other considerations?