6
Describing Elements
Warm-Up
Which statements accurately describe elements? Check all that apply
Elements are made up of two or more types of atoms,
Elements are made up of only one type of atom
Each element has a unique chemical symbol
Elements can be identified by their atomic number
One element cannot be combined with another element.

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.