Telescoping Trailer Tongue Extension Question

mkirsch wrote:

First off the structure of the telescoping tongue only ADDS weight to the tongue.

I think we can safely neglect the weight of the added metal for this setup. The point is that when extended you have a longer lever arm than when retracted. If the center of gravity is a fixed distance in front of the trailer axle, this moment must be offset by the moment produced at the hitch. Since we know the trailer is not spinning end over end, the sum of the moments must be equal to zero; and this must be true for both the extended and retracted positions. The weight at the tongue therefore changes. In the extreme example, the tongue weight requiring a jack will be easily lifted with one finger when the lever arm is made long enough.