I just wanted to make a statement about conservation of momentum. Linear momentum and angular momentum are different animals and can not be converted freely.
Recently, I have seen proposals that suggest that one can convert linear momentum into angular momentum and that is clearly not possible. You can visualize linear momentum as pertaining to motion of an object or group of objects that are progressing as a group past an observer. The center of mass of the objects is in motion and can be used to calculate the total linear momentum of the subjects. Angular momentum is measured and calculated by observing the rotation of the center of mass of a system of objects. Think of a planet in motion around its central star as an example of this type of momentum. An observer can be stationary with respect to the center of mass of the objects and calculate the magnitude of the collective angular momentum they contain. And, since he is stationary with respect to the center of mass of the objects, they have no linear momentum according to his determination. Any forces which operate between the collection of objects taken as a system are not able to convert angular momentum into linear momentum or vice versa. Dave
