How much work would be done by an external agent to bring two planets (each with a mass of 1x10^20 kg) to a separation distance of 3.0x10^10 m (center to center)

Air is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. air enters the heat exchanger at 95 kpa and 20°c at a rate of 0.6 m^3/s. the combustion gases (cp = 1.10 kj/kg°c) enter at 160°c at a rate of 0.95 kg/s and leave at 95°c. determine the rate of heat transfer to the air and its outlet temperature.

The mantle is made up of which structural zones?

Which form of cell division creates the sperm and egg, resulting in half of the chromosomes as the other cells?