Ah hah ! Thank you for that data at the end ... about the 2.5kg box.
I thought we were going to have to calculate it from Square-1.
Without checking, I'll assume that a 2.5kg box at that location really
does weigh 6.1 Newtons.
Weight (gravitational force) is directly proportional to the mass of
the object ... if you eat twice as much, you'll weigh twice as much.
So the weight of the 1kg box is
(1 / 2.5) x (6.1 N) = 2.44 Newtons .
