# Fluid Mechanics and Thermal Sciences (Test 1)

## Gate Exam : Me Mechanical Engineering

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Q.1
Two large diffuse gray parallel plates, separated by a small distance, have surface temperatures of 400 K and 300 K. If the emissivities of the surfaces are 0.8 and the Stefan-Boltzmann constant is 5.67 × 10-4 W / m2 K4, the net radiation heat exchange rate in kW / m2 between the two plates is
A. 0.66
B. 0.79
C. 0.99
D. 3.96
Explaination / Solution: Workspace
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Q.2
The crank radius of a single–cylinder I. C. engine is 60mm and the diameter of the cylinder is 80mm. The swept volume of the cylinder in cm3 is
A. 48
B. 96
C. 302
D. 603
Explaination / Solution:

Stroke of the cylinder l = 2r = 2 × 60 = 120mm
Swept volume = (π/4)d2 × I = (π/4) × 802 × 120 = 603 cm3

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Q.3
A compressor undergoes a reversible, steady flow process. The gas at inlet and outlet of the compressor is designated as state 1 and state 2 respectively. Potential and kinetic energy changes are to be ignored. The following notation are used: v = specific volume and P = pressure of the gas. The specific work required to be supplied to the compressor for this gas compression process is
A. B. C. v1 = (P2 - P1)
D. -P2(v1 - v2)
Explaination / Solution:
No Explaination.

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Q.4
You are asked to evaluate assorted fluid flows for their suitability in a given laboratory application. The following three flow choices, expressed in terms of the two-dimensional velocity fields in the x-y plane, are made available.
P. u = 2y, v = -3x; Q. u = 3xy, v = 0; R. u = -2x, v = 2y
Which flows(s) should be recommended when the application requires the flow to be incompressible and irrotational?
A. P and R
B. Q
C. Q and R
D. R
Explaination / Solution:
No Explaination.

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Q.5
Match the items in Column I and Column II.
Column I                                 Column II
P. Metallic Chills                      1. Support for the core
Q. Metallic Chaplets                2. Reservoir of the molten metal
R. Riser                                   3. Control cooling of critical sections
S. Exothermic Padding           4. Progressive solidification
A. P-1, Q-3, R-2, S-4
B. P-1, Q-4, R-2, S-3
C. P-3, Q-4, R-2, S-1
D. P-4, Q-1, R-2, S-3
Explaination / Solution:
No Explaination.

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Q.6
A hydraulic turbine develops 1000kW power for a head of 40m. If the head is reduced to 20m, the power developed (in kW) is
A. 177
B. 354
C. 500
D. 707
Explaination / Solution:
No Explaination.

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Q.7
A fin has 5mm diameter and 100mm length. The thermal conductivity of fin material is 400Wm-1K-1. One end of the fin is maintained at 130ºC and its remaining surface is exposed to ambient air at 30ºC. if the convective heat transfer coefficient is 40Wm-2K-1, the heat loss (in W) from the fin is
A. 0.08
B. 5.0
C. 7.0
D. 7.8
Explaination / Solution:
No Explaination.

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Q.8
Match the following pairs: A. P - IV,Q - I, R - II,S - III
B. P - IV,Q - III, R - I,S - II
C. P - III,Q - I, R - IV,S - II
D. P - III,Q - I, R - II,S - IV
Explaination / Solution:
No Explaination.

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Q.9
The speed of an engine varies from 210 rad/s to 190 rad/s. During the cycle the change in kinetic energy is found to be 400 Nm. The inertia of the flywheel in kg/m2 is
A. 0.10
B. 0.20
C. 0.30
D. 0.40
Explaination / Solution:
No Explaination.

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Q.10
A heat transformer is device that transfers a part of the heat, supplied to it at an intermediate temperature, to a high temperature reservoir while rejecting the remaining part to a low temperature heat sink. In such a heat transformer, 100 kJ of heat is supplied at 350 K. The maximum amount of heat in kJ that can be transferred to 400 K, when the rest is rejected to a heat sink at 300 K is
A. 12.50
B. 14.29
C. 33.33
D. 57.14