The general formula is: Momentum = (mass) x (speed)
I never like to just write a bunch of algebra without explaining it.
But in this particular case, there's really not much to say, and
I think the algebra will pretty well explain itself. I hope so:
Original momentum = (original mass) x (original speed)
New momentum = (2 x original mass) x (2 x original speed)
= (2) x (original mass) x (2) x (original speed)
= (2) x (2) x (original mass) x (original speed)
= (4) x (original mass) x (original speed)
= (4) x (original momentum).
Electromagnets are used for various purposes but I fathom in this instance, the questioner is asking about how electromagnetics can be used to attraction or repulsion.
Example, electromagnets are used for attraction in cranes which attach them to containers in order to lift them.
Meanwhile, Maglev trains use electromagnets repulsive properties.
The water will be cool and steam will be created by the hot and cold water reacting together