. Mr. Bradley boils water to make a cup of hot tea. As the water begins to boil, a current forms when the molecules of water in the pot are heated, and they move and take their energy with them. Which form of energy transfer is causing the movement of the water molecules? A. conduction C. insulation
B. convection D. radiation

lithosphere and asthenosphere

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.