12. Determine whether each of the following objects is an insulator or a conductor.

A sample of sand has the following properties: Moist mass625.2 g%3D Dry mass589.9 g%3D Absorption = 1.6 Determine (a) total moisture content and (b) free moisture content.

The wear resistance of a steel shaft is to be improved by hardening its surface. This is to be accomplished by increasing the nitrogen content within an outer surface layer as a result of nitrogen diffusion into the steel. The nitrogen is to be supplied from an external nitrogen-rich gas at an elevated and constant temperature. The initial nitrogen content of the steel is 0.002 wt%,whereas the surface concentration is to be maintained at 0.50 wt%. For this treatment to be effective, a nitrogen content of 0.10 wt% must be established at a position 0.40 mm below the surface. Specify appropriate heat treatments in terms of temperature and time for temperatures-between 475°C and 625°C. Calculate values for 500°C, 550°C, 600°C temperatures that lie-within the range stipulated in the problem. The pre-exponential and activation energy for the-diffusion of itrogen in iron are 3 × 107 m/s and 76150 J/mol, respectively, over this temperature range. (8 marks including 2 marks for each final answer in the table and 3marks for the solution)

Q1: (a) From the plot of yield strength versus(grain diameter) 1/2 for a 70 Cu-30 Zn cartridge brass in the figure below, determine values for the constants So and Ky. (b) Now predict the yield strength of this alloy when the average grain diameter is 103 mm.

QUESTION 6 In an automotive sheet metal part, the shown hole shape is required to be punched to provide access to wiring and maintenances in the floor panel. The sheet is made of Al 1100-O material with 0.2mm thickness. Estimate the force required to punch the by using flat dies?

Q5: For 11.20 kg of a magnesium-lead alloy of composition 30 wt% Pb70 wt% Mg, is it possible, at equilibrium, to have a and Mg,Pb phase shaving respective masses of 7.39 kg and 3.81 kg? If so, what will be the approximate temperature of the alloy? If such an alloy is not possible,explain why.

15. A new type of insulating board has been developed by that esteemed construction organisation Kaput Co. They warn that at extremely high heat fluxes it could be ignited, but they don't think it's very likely and it would take hours, so there's no real risk!As an expert on the ignitability of materials, you are asked to perform a thick/thin calculation given the following data on the material: Density 2300kg m3 Thermal conductivity 0.85W m-1 K-1 Specific heat capacity 847J kg1 K1 Thickness of board 8mm Initial/ambient laboratory temperature18°C Ignition temperature 415°C

. A small wooden crib burns on the floor in the middle of a room. With a total energy release rate of 150kW. Calculate the mass flow in the plume at heights of 2m and 4m above the floor. Also calculate the plume temperatures at these heights. Assume the radiative fraction of energy loss is 25%. Assume ambient room temperature of 20°C. Explain your answers.

50 kg of gravel is mixed with 30 kg of sand. The gravel has a moisture content of3.9% and absorption of 4.7%, whereas the sand has a moisture content of 3.5%and absorption of 4.9%. What is the amount of water required to increase the moisture contents of both gravel and sand to reach absorption? Why is it important to determine the amount of water required to increase the moisture content of aggregate to reach absorption?

a. The shape and surface texture of aggregate particles are important for both Portland cement concrete and asphalt concrete.or rough and (1) For preparing PCC, would you prefer round and smooth aggregate or rough and angular aggregate and why? (II). For preparing HMA, would you prefer round and smooth aggregate or rough and

A sieve analysis test was performed on a sample of aggregate and producedA sieve analysis test was performed on a sample of aggregate and prod.the results shown in Table P5.21..21 Calculate the percent passing through each sieve. Plot the percent passing versus sieve size on: a. a semilog gradation chart, and b. a 0.45 gradation chart (Figure A.25).What is the maximum size? What is the nominal maximum size?