29. Uniaxial compression test data for a solid metal bar of length 1 m is shown in the figure. (MPa) 130 R P 100 FORD (mm/mm) The bar material has a linear elastic response from O to P followed by a non-linear response. The point P represents the yield point of the material. The rod is pinned at both the ends. The minimum diameter of the bar so that it does not buckle under axial loading before reaching the yield point is (round off to one decimal place). mm 30. Keeping all other parameters identical, the Compression Ratio (CR) of an air standard diesel cycle is increased from 15 to 21. Take ratio of specific heats = 1.3 and cut-off ratio of the cycle rc = 2. The difference between the new and the old efficiency values, in percentage, (nnew |CR-21)-(nold |CR-15) %. (round off to one decimal place). 31. A thin-walled cylinder of radius r and thickness t is open at both ends, and fits snugly between two rigid walls under ambient conditions, as shown in the figure. Rigid wall Rigid wall Pressure vessel The material of the cylinder has Young's modulus E, Poisson's ratio v, and coefficient of thermal expansion a. What is the minimum rise in temperature AT of the cylinder (assume uniform cylinder temperature with no buckling of the cylinder) required to prevent gas leakage if the cylinder has to store the gas at an internal pressure of p above the atmosphere? (A) ATv+ 1 pr 2 AT=(v+JatE (C) ATV- 1 pr 4 atE 3vpr (B) AT= 2atE vpr (D) AT= atE 32. The spectral distribution of radiation from a black body at T = 3000 K has a maximum at wavelength Amax. The body cools down to a temperature T2. If the wavelength corresponding to the maximum of the spectral distribution at T2 is 1.2 times of the original wavelength max, then the temperature T is K (round off to the nearest integer). 33. A cylindrical bar with 200 mm diameter is being turned with a tool having geometry 0 9 -7 -8 -15 - 30 0.05 inch (Coordinate system, ASA) resulting in a cutting force Fc1. If the tool geometry is changed to 0 9 -7 -8 -15 0 0.05 inch (Coordinate system. ASA) and all other parameters remain unchanged, the cutting force changes to Fc2. Specific cutting energy (in J/mm) is U = U (t)04, where Uo is the specific energy coefficient, and t is the -0.4 uncut thickness in mm. The value of percentage change in cutting force Fc2, i.e. is (round off to one decimal place). Fc2-Fl F1 100, 34. Water (density 1000 kg/m) flows through an inclined pipe of uniform diameter. The velocity, pressure and elevation at section A are VA = 3.2 m/s, PA 186 kPa and ZA = 24.5 m, respectively, and those at section B are VB = 3.2 m/s, PB = 260 kPa and ZB = 9.1 m, respectively. If acceleration due to gravity is 10 m/s then the head lost due to friction is m (round off to one decimal place).