Fluid Mechanics (161-180)

Updated: Apr 21, 2020

161. If the depth of flow in a channel is 1 m and velocity of flow is 2 m/sec. then the

velocity with which an elementary wave can travel upstream is 1.132 m/sec

162. The height of hydraulic jump is equal to difference in conjugate depths

163. If the conjugate depths before and after the jump are 0.5 m and 2.5 m respectively, then the loss of energy in the hydraulic jump will be 1.6 m

164. The specific energy in m kg/kg for the flow expressed by V=2.22 m/sec and y = l m is 1.25

165. The value of Froude number can be Any no

166. The pressure coefficient is the ratio of pressure forces to inertial forces


167. Select the non-dimensional parameter of the following specific gravity

168. Which of the following is not a non dimensional parameter ? Chezy's coefficient

169. The dimensions of pressure gradient dp/dx in a fluid are M¹L⁻²T⁻²

170. Which of the following quantities is dimensionless ?






where F is force, p is density and u is dynamic viscosity and the dimensions of

dynamic viscosity are M¹ L⁻¹ T⁻¹ .


I71. Froude number is the ratio of inertia force to gravity force

172. If the physical quantities involved in a fluid flow phenomenon are discharge 0.

diameter D, acceleration due to gravity g, dynamic viscosity μ. and density p, then

the number of n parameters needed to express the function F (Q, D, g, μ, p) = 0 2

173. In a 1 : 100 scale model of a harbour, the time which will correspond to the

prototype tidal period of 12 hours will be 1.2 hours

174. If the resistance R to the motion of a sphere through a fluid is a function of the density p, viscosity η of the fluid, radius r and velocity v of the sphere, the number of π-parameters needed to express the

function F (R, p, η, r, v) = 0 is 2

175. The dimensions of surface tension are M¹L⁰T²

176. Which of the following is a dimensionally homogeneous equation ?



177. Apart from inertia force, which of the following forces is most important in

motion of submarines under water ? viscous force


178. In which of the following situations, the viscous force is unimportant ?

capillary waves in channels

179. The ratio of volume flow rates in two dynamical similar systems governed by

Froude modelling is equal to (assume g=1 )



180. Which of the following could be a n parameter of the function (Φ (F, V, ρ, μ,

L)= 0 when V, ρ and L are taken as repeating variables ?


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