Aheat engine absorbs 3120 j of heat from
a hot reservoir and expels 720 j to a cold
reservoir. when it is run in reverse, with the
same reservoirs, the engine pumps 3120 j of
heat to the hot reservoir, requiring 2400 j of
work to do so.
find the ratio of the work done by the heat
engine to the work done by the pump.

B. a circuit. i think

Answer;

hot magma rises and pushes up toward the lithosphere, and as it cools it cycles back down toward the core to be heated again.

explanation; convection currents are the circular pathways taken by a fluid that enhances heat transfer by the process known as convection which occurs in fluids.convection currents transfer heat from one place to another by mass motion of a fluid. earth mantle is in a semi-liquid state and behaves like any other fluid, rising up from the bottom of the mantle after becoming hotter and less dense from heat of the earth's core, as the rock loses heat into the earth's crust it becomes cooler and more dense, then sinking back down to the core, then repeating the cycle.