Consider the one-dimensional wall shown in the sketch, which is initially at a uniform temperature ti and is suddenly subjected to the convection boundary condition with a fluid at t[infinity]. for a particular wall, case 1, the temperature at x = l1 after t1 = 100 s is t1(l1, t1) = 315°c. another wall, case 2, has different thickness and thermal conditions as shown. case l (m) α (m2/s) k (w/m · k) ti (°c) t[infinity] (°c) h (w/m2 · k) 1 0.10 15 × 10−6 50 300 400 200 2 0.40 25 × 10−6 100 30 20 100 how long will it take for the second wall to reach 28.5°c at the position x = l2? use as the basis for analysis, the dimensionless functional dependence for the transient temperature distribution expressed in equation 5.41.

People with normal vision cannot focus their eyes underwater if they aren't wearing a face mask or goggles and there is water in contact with their eyes. in a simplified model of the human eye, the aqueous and vitreous humors and the lens all have a refractive index of 1.40, and all the refraction occurs at the cornea, whose vertex is 2.60 cm from the retina.with the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 2.05cm in front of the eye.)