We can apply a torque to give momentum 'L' to the blue flywheel. Assume no friction so no momentum is transferred to the baseplate.
Now we do the same, but though reversing gears (again no friction), we supply angular momentum 'L' and the flywheel gains -L momentum. Therefore to conserve angular momentum, 2*L must be transferred to the baseplate.
Can we show the magnitude of the angular momentum transferred to the baseplate by calculating the forces instead of using the conservation law?
Does the offset in axies affect the result?
Further Information
These pages contain examples to illustrate the principles involved, for an discussion of the theory about angular momentum see this page.
