At what point will the heat flow stop?

When you put a hot object in contact with a cold one it heat will flow from the warmer to the cooler. and as a result the warmer one will be usually cool down and the cooler one will usually warm up. Eventually, they will reach the same temperature and heat flow will stop.

Explanation: Hope this helps

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).