##### Q31. The velocity components in the x- and y-directions of a two dimensional potential flow are u and v, respectively. Then ∂u/∂y is equal to

(a) ∂v/∂x
(b)  – ∂v/∂x
(c) ∂v/∂y
(d) – ∂v/∂y                                                                                                                   (GATE-ME-2005)

Ans: (a) ∂v/∂x

##### Q32. In a Pelton wheel, the bucket peripheral speed is 10 m/s, the water jet velocity is 25 m/s and volumetric flow rate of the jet is 0.1 m3/s. If the jet deflection angle is 120°C and the flow is ideal, the power developed is

(a) 7.5 kW
(b) 15.0 kW
(c) 22.5 kW
(d) 37.5 kW.                                                                                                                  (GATE-ME-2006)

Ans: (c) 22.5 kW

##### Q33. The SI unit of kinematic viscosity (v) is

(a) m2/sec
(b) kg/m-sec
(c) m/sec2
(d) m3/sec2.                                                                                                           (GATE-ME-2001)

Ans: (a) m2/sec

##### Q34. The dimension of surface tension is

(a) ML–1
(b) L2T–1
(c) ML–1 T–1
(d) MT–2.                                                                                                             (GATE-ME-1996)

Ans:  (d) MT–2

##### Q35. For laminar flow through a long pipe, the pressure drop per unit length increases

(a) in linear proportion to the cross-sectional area
(b) in proportion to the diameter of the pipe
(c) in inverse proportion to the cross-sectional area
(d) in inverse proportion to the square of cross-sectional area.           (GATE-ME-1996)

Ans:  (c) in inverse proportion to the cross-sectional area

##### Q36. In order to have maximum power from a Pelton turbine, the bucket speed must be

(a) equal to the jet speed
(b) equal to half of the jet speed
(c) equal to twice the jet speed
(d) independent of the jet speed.                                                                  (GATE-ME-2013)

Ans:  (b) equal to half of the jet speed

##### Q37. A journal bearing has a shaft diameter of 40 mm and a length of 40 mm. The shaft is rotating at 20 rad/s and the viscosity of the lubricant is 20 mPa-s. The clearance is 0.020 mm. The loss of torque due to the viscosity of the lubricant is approximately

(a) 0.040 Nm
(b) 0.252 Nm
(c) 0.400 Nm
(d) 0.652 Nm                                                                                            (GATE-ME-2008)

Ans:  (a) 0.040 Nm

##### Q38. For a fluid element in a two dimensional flow field (x-y plane), it will undergo

(a) translation only
(b) translation and rotation
(c) translation and deformation
(d) deformation only.                                                                               (GATE-ME-1994)

Ans:  (b) translation and rotation

##### Q39. Two pipes of uniform section but different diameters carry water at the same volumetric flow rate. Water properties are the same in the two pipes. The Reynolds number, based on the pipe diameter

(a) is the same in the both pipes
(b) is large in the narrow pipe
(c) is smaller in the narrower pipe
(d) depends on the pipe material.                                                       (GATE-PI-2008)

Ans:  (b) is large in the narrow pipe

##### Q40. An incompressible fluid (kinematic viscosity = 7.4 × 10–7 m2/s, specific gravity, 0.88) is held between two parallel plates. If the top plate is moved with a velocity of 0.5 m/s while the bottom one is held stationary, the fluid attains a linear velocity profile in the gap of 0.5 mm between these plates; the shear stress in Pascal on the surface of bottom plate is

(a) 0.651 × 10–3
(b) 0.651
(c) 6.51
(d) 0.651 × 103.

Ans:  (b) 0.651

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