The main characteristic of a carbon sink is that
a. it emits no carbon
b. it absorbs no carbon
c. it emits more carbon than it absorbs
d. it absorbs more carbon than it emits

The correct answer is D. It absorbs more carbon than it emits.

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.