A student left a jar of water outside his home. Water can be a solid, liquid, or gas. When he put the jar outside, the water was liquid. Twelve hours later, the water had changed phase and was
a gas.
What happened to the water molecules?

the answer is a! (2.9 x 10^-18 j) hope i could someone. : )

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.