Q. 8 Critical damping is the (A) largest amount of damping for which no oscillation occurs in free vibration (B) smallest amount of damping for which no oscillation occurs in free vibration (C) largest amount of damping for which the motion is simple harmonic in free vibration (D) smallest amount of damping for which the motion is simple harmonic in free vibration Q. 11 A rigid link PQ is 2 m long and oriented at 20 to the horizontal as shown in the figure. The magnitude and direction of velocity Vo, and the direction of velocity Vp are given. The magnitude of Vp (in m/s) at this instant is V = 1 m/s 45 (A) 2.14 (C) 1.21 20 Vp (B) 1.89 (D) 0.96 Q. 20 0.50) For machining a rectangular island represented by coordinates P(0,0), Q(100,0), R(100,50) and S(0,50) on a casting using CNC milling machine, an end mill with a diameter of 16 mm is used. The trajectory of the cutter centre to machine the island PQRS is (A) (-8, 8), (108, - 8), (108,58), (-8,58), (-8, -8) (B) (8, 8), (94, 8), (94, 44), (8, 44), (8, 8) (C) (-8,8), (94, 8), (94, 44), (8, 44), (-8,8) (D) (0, 0), (100, 0), (100, 50), (50, 0), (0, 0) Q. 21 Which one of the following instruments is widely used to check and calibrate geometric features of machine tools during their assembly? (A) Ultrasonic probe (B) Coordinate Measuring Machine (CMM) (C) Laser interferometer (D) Vernier calipers Q. 22 The major difficulty during welding of aluminium is due to its (A) high tendency of oxidation (C) low melting point (B) high thermal conductivity (D) low density