So the best conductor for electricity is silver.
However because silver is so expensive we use copper which is the next best conductor
If the net force is 4 N, and Frankie is pulling the rope with 7 N, Carol must be pulling the rope with 11 N (I think that Carol is going to win the tug-of-war...).
It would become a type of metamorphic rock. Most likely marble
If the compressor removes 500 j if the 700 the 200 j left would have Ben conducted through the refrigerator/200 j released into the room