Why is nonpoint source pollution potentially more harmful than point source pollution?
a. nonpoint source pollution disrupts the water cycle.
b. nonpoint source pollution is difficult to regulate.
c. nonpoint source pollution comes from more than one source.
d. nonpoint source pollution is more damaging to living organisms than point source pollution

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.