It is much easier to slice a piece of pie with the edge of a sharp knife than with the edge of a pencil. Explain this in terms of applied pressure. Just Putting this out there for other students

The Knife will have more pressure than the edge of a pencil because it has less area. The pencil will have less pressure than the knife because it has more area.

Note: As pressure increases the area will decrease and as the area increases the pressure will decrease.

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.