September 2023

Q. Assuming ISA standard sea level conditions (288.16 K, density of 1.225 kg/m3, g = 9.81 m/s2, R = 287 J/(kg-K)), the density (in kg/m3) of air at Leh, which is at an altitude of 3500 m above mean sea level is (accurate to two decimal places). Ans: 0.85 to 0.88

Q. A rocket has an initial mass of 150 kg. After operating for a duration of 10 s, its final mass is 50 kg. If the acceleration due to gravity is 9.81 m/s2 and the thrust produced by the rocket is 19.62 kN, the specific impulse of the rocket is (A) 400 s                                           (B) 300

Q. An axial compressor that generates a stagnation pressure ratio of 4.0, operates with inlet and exit stagnation temperatures of 300 K and 480 K, respectively. If the ratio of specific heats (𝛾) is 1.4, the isentropic efficiency of the compressor is (A) 0.94                                           (B) 0.81 (C) 0.72                               (D) 0.63 Ans: 0.81

Q. A solid circular shaft of diameter d is under pure torsion of magnitude T. The maximum tensile stress experienced at any point on the shaft is Ans: Option D

Q. A thin airfoil is mounted in a low-speed, subsonic wind tunnel, in which the Mach number is 0.1. At a point on the airfoil, the pressure coefficient is measured to be –1.2. If the flow velocity is increased such that the free-stream Mach number is 0.6, the pressure coefficient at the same point on

Q. The relation between pressure (p) and velocity (V) for a steady, isentropic flow at two points along a streamline is, (c is a constant) Ans: Option C

Q. The stagnation pressures at the inlet and exit of a subsonic intake are 100 kPa and 98 kPa, respectively. The pressure recovery of this intake will be  Ans: 0.50 to 0.50

Q. For a damped single degree of freedom system with damping ratio of 0.1, ratio of two successive peak amplitudes of free vibration is  Ans: 1.75 to 1.95