TQ8: The hull of the space shuttle consists of ceramic tiles bonded to an aluminium skin. Discuss the design requirements of the shuttle hull that led to the use of this combination of materials. What problems in producing the hull might the designers and manufacturers have faced? TQ9: You would like to select a material for the electrical contacts in an electrical switching device which opens and closes frequently and forcefully. What properties should the contact material possess? What type of material might you recommend? Would A120; be a good choice? Explain. TQ10:Aluminium has a density of 2.7 Mg.m³. Suppose you would like to produce a composite material based on aluminium having a density of 1.5 Mg.m³. Design a material that would have this density. Would introducing beads of polyethylene, with a density of 0.95 Mg.m³, into the aluminium be a likely possibility? Explain. TQ11:You would like to be able to identify different materials without resorting to chemical analysis or lengthy testing procedures. Describe some possible testing and sorting techniques you might be able to use based on the physical properties of materials. TQ12: You would like to be able to physically separate different materials in a scrap recycling plant. Describe some possible methods that might be used to separate materials such as polymers, aluminium alloys, and steels from one another. TQ13:Some pistons for automobile engines might be produced from a composite material containing small, hard silicon carbide particles in an aluminium alloy matrix. Explain what benefits each material in the composite may provide to the overall part. What problems might the different properties of the two materials cause in producing the part TQ14:Allowed values for the quantum numbers of electrons are as follows: 10. 1. 2. 3. Relative to the subshells. 10 corresponds to an s subshell 1=1 corresponds to a p subshell 1=2 corresponds to a d subshell 13 corresponds to an/subshell For the K shell, the four quantum numbers for each of the two electrons in the 1s state, in the order of nlmm, are 100 and 100(-) Write the four quantum numbers for all the electrons in the Land M shells, and note which correspond to the sp. and d subshells.