# Fluid dynamics | GATE MCQs (solved)

## GATE ME solved Questions on Fluid Dynamics

Question #1

A sprinkler shown in the figure rotates about its hinge point in a horizontal plane due to water flow discharged through its two exit nozzles.The total flow rate Q through the sprinkler is 1 litre/sec and the cross-sectional area of each exit nozzle is 1 cm 2. Assuming equamyml flow rate through both arms and a frictionless hinge, the steady state angular speed of rotation (in rad/s) of the sprinkler is ______ (correct to two decimal places).

[GATE 2018 Set 1, 2 marks]

Question #2

Air flows at the rate of 1.5 m3 /s through a horizontal pipe with a gradually reducing cross- section as shown in the figure. The two cross-sections of the pipe have diameters of 400 mm and 200 mm. Take the air density as 1.2 kg/m3 and assume inviscid incompressible flow. The change in pressure $(P_2-P_1)$ (in kPa) between sections 1 and 2 is

[GATE 2018 Set 2, 2 marks]

Question #3

A frictionless circular piston of area $10^{-2}m^2$  and mass 100 kg sinks into a cylindrical container of the same area filled with water of density 1000 kg/m3 as shown in the figure.The container has a hole of area $10^{-3}m^2$ at the bottom that is open to the atmosphere.

Assuming there is no leakage from the edges of the piston and considering water to be incompressible, the magnitude of the piston velocity (in m/s) at the instant shown is _____ (correct to three decimal places).

Question #4

A 60 mm-diameter water jet strikes a plate containing a hole of 40mm diameter as shown in the figure. Part of the jet passes through the hole horizontally, and the remaining is deflected vertically. The density of water is 1000 kg/ m3. If velocities are as indicated in the figure, the magnitude of horizontal force (in N) required to hold the plate is _________

[GATE 2017 Set 2, 2 marks]

Question #5

The arrangement shown in the figure measures the velocity V of a gas of density 1 kg/m3 flowing through a pipe. The acceleration due to gravity is 9.81 m/s . If the manometric fluid is water (density 1000 kg/m3) and the velocity V is 20 m/s, the differential head h (in mm) between the two arms of the manometer is
____________

[GATE 2017 Set 2, 2 marks]

Question #6

The water jet exiting from a stationary tank through a circular opening of diameter 300 mm impinges on a rigid wall as shown in the figure. Neglect all minor losses and assume the water level in the tank to remain constant. The net horizontal force experienced by the wall is ___________ kN.
Density of water is 1000 kg/m3

Acceleration due to gravity g = 10 m/s2

[GATE 2016 Set 3, 2 marks]

Question #7

Water ($\rho =1000kg/m^3$ ) flows through a venturimeter with inlet diameter 80 mm and throat diameter 40 mm. The inlet and throat gauge pressures are measured to be 400 kPa and 130 kPa respectively. Assuming the venturimeter to be horizontal and neglecting friction, the inlet velocity (in m/s) is _______

[GATE 2015 Set 1, 2 marks]

Question #8

A Prandtl tube (Pitot-static tube with C=1) is used to measure the velocity of water. The differential manometer reading is 10 mm of liquid column with a relative density of 10. Assuming g = 9.8 m/s2 , the velocity of water (in m/s) is ________

[GATE 15 S3, 2 marks]

Question #9

An ideal water jet with volume flow rate of 0.05 m3/s strikes a flat plate placed normal to its path and exerts a force of 1000 N. Considering the density of water as 1000 kg/m3 , the diameter (in mm) of the water jet is _______

[GATE 2014 Set 1, 2 marks]

Question #10

A siphon is used to drain water from a large tank as shown in the figure below. Assume that the level of water is maintained constant. Ignore frictional effect due to viscosity and losses at entry and exit. At the exit of the siphon, the velocity of water is

[GATE 2014 Set 3, 2 marks]

Practice other topics from Fluid Mechanics:

Properties of fluid

Fluid Statics

Flow through pipes

Boundary layer theory

Turbomachinery and Dimensional analysis