Which of the following is a true statement about science?
a. science can be defined as a body of knowledge about the natural world. b. scientific knowledge is continually being extended, refined, and revised. c. scientific ideas are able to be modeled during investigations.
d. all of these

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.