Ally sees a photograph of a macaroni penguin that lives in South Georgia, a sub-Antarctic island. She reads more about these penguins and learns that they mate for life. She knows that not all animals mate for life and that there are various combinations of mating systems. Describe two mating systems, and explain why different systems exist. (science 7th grade)

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.