A pulley with 19.5 kilograms suspended from one side and 20.5 kilograms on the other side will have a final velocity of .70036 m/sec after the one extra kilogram has dropped one meter; this is 28.014 units of momentum.  (40 kg x .70036 m/sec)
A one kilogram object with 28.014 units of momentum will rise 40 meters: but the one kilogram was only dropped one meter. This is a 4000% increase in the quantity of energy.
The rotation of despin devices will return to the original rotation rate if the cable is left attached. This means that the big object has given all of its momentum to the small object. The 40 kilogram pulley arrangement can give all of its momentum to the extra one kilogram; for a massive energy increase.

-It is really extremely simple: If the motion of a larger mass can be transferred to a small mass the energy goes up.

Ten kilograms moving one meter per second has 10 units of momentum and 5 joule of energy.

One kilogram of mass moving 10 m/sec has 10 units of momentum and 50 joules of energy.

Look at the despin of the Dawn Mission satellite. When the rotation of the satellite is stopped the weights have all the momentum. Because; if the weights are left attached the original rotation would be returned to the satellite. At the point when the weights have all the motion; the energy increase is unimaginably large.

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