A thick oak wall, initially at 25 oC, is suddenly exposed to combustion products for which T[infinity] = 800 oC and h = 20 W/m^2 ⋅ K. (a) Determine the time of exposure required for the surface to reach the ignition temperature of 400 oC.
(b) Plot the temperature distribution T(x) in the medium at t = 325 s. The distribution should extend to a location for which T ≈ 25 oC.

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.

The pressure on how fast or slow the car is going