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Jul28-09, 09:17 AM
P: 4,054
Quote Quote by dgreenheck View Post
This makes sense. So I'm probably just getting the illusion that when I push something at the end, less of the force is going into the linear component because it rotates,
Or you are even applying less force, because it resists less to rotation. It is hard to control the amount of force you apply to an object which is not fixed.

Quote Quote by dgreenheck View Post
One more example and then I'll drop this thread: if I have a rocket engine aimed directly away from the center of mass, it should push the object perfectly forward with no torque. However, if I put the rocket engine off center, it will go into a wild spin and it will barely make any progress. Is this just because the tangential velocity of the rocket changes, constantly canceling out any forces acting upon it?
The engine rotates with the rocket so the direction of the linear acceleration changes too, if you fire the engine continuously. But you can still get somewhere, when you fire the rocket in short bursts, just when the engine points in the desired direction. If you had two opposing off center engines you could fire them alternating after half rotation avoiding spinning up more and more. Since you don't put any energy into rotation, this should be quite efficient in terms of terminal velocity / fuel spent.