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5. For the following materials/situations, determine the maximum thickness (or diameter for cylinders or spheres) for which the lumped capacitance model can be used (i.e., Bi = 0.1) and the

temperature of the object can be assumed to be uniform throughout the material as it heats or cools. A. A large flat sheet of tin is cooled from 400 K to 350 K by dropping it in a large vat of water at 298 K with hwater= 138.7 W/m?-K. (you may look up ktin @ 400K) B. A large flat sheet of plate glass is cooled from 400 to 350 K by dropping it in a large vat of water at 298 K with hwater = 138.7 W/m?-K (you may look up kglass @ 300K) C. A solid cylinder made of tin is initially at 400 K and cools in a large vat of water at 298 K with hwater = 138.7 W/m^2-K D. A solid cylinder made of tin is initially at 400 K and cools using air at 298 K with hair = 27.4 W/m²-K E. A solid sphere made of aluminum is heated from 300 K using air at 500 K with hair = 41.7 W/m^2-K F. A hot pancake at 330 K is flipped in the air at 298 K with hair = 27.4 W/m²-K You may treat the pancake as cooked cake batter - and look up k at 300 K (it's in our appendix!). You should treat the pancake as a flat disc (i.e. a slab geometry, not a cylinder). G. A donut hole (spherically-shaped cooked cake batter) comes out of the fryer at 400 K and is cooled by air at 298 K with hair = 27.4 W/m^2-K. H. A donut hole (spherically-shaped cooked cake batter) comes out of the fryer at 400 K and is cooled by air using a fan at 298 K with hair = 88.5 W/m²-K.

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