NHPC JE'21 ME: Daily Practices Quiz. 11-Oct-2021

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NHPC-JE’21 ME: Daily Practices Quiz

NHPC-JE’21 ME: Daily Practices Quiz 11-Oct-2021

Quiz: Mechanical Engineering
Exam: NHPC
Topic: Machine Design

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 6 Minutes

Q1. The wet bulb temperature is a measure of which humidity?
(a) Relative
(b) Absolute
(c) Specific
(d) None of the above

Q2. The curved lines on Psychrometric chart indicate
(a) Specific humidity
(b) Relative humidity
(c) Dew point temperature
(d) Dry bulb temperature

Q3. When heat is transferred from one particle of hot body to another by actual motion of the heated
particle, it is referred to as heat transfer by
(a) conduction
(b) convection
(c) radiation
(d) conduction and convection

Q4. An ideal gas at 27°C is heated at constant pressure till its volume becomes two times. The temperature of gas then will be
(a) 81°C
(b) 900°C
(c) 600°C
(d) 327°C

Q5. Which one of the following non-dimensional numbers is used for transition from laminar to turbulent flow in free convection?
(a) Reynolds number
(b) Grashoff number
(c) Peclet number
(d) Rayleigh number

Q6. The component of torque converter that allows torque multiplication is
(a) Turbine
(b) Impeller
(c) Stator
(d) Freewheel

Solutions

S1. Ans. (b)
Sol. Absolute

S2. Ans. (b)
Sol. Relative humidity

S3. Ans. (a)

S4. Ans. (d)
Sol. At constant pressure. According to Charle’s law
V α T
V_1/V_2 =T_1/T_2
T_2=(V_2/V_1 ) T_1 [V_2=2V_1 ]
= 2T1 = 2(27 + 273)
T2 = 600 K = 327°C

S5. Ans (d)
Sol. Rayleigh number is used to determine whether the flow is laminar or turbulent in natural convection.
Ra<10^8 Laminar
10^8<Ra<10^10 Transaction
Ra>10^10 Turbulent

S6. Ans (c)
Sol. A hydraulic torque converter consists of series of fixed guide vanes which are provided between turbine runner and pump impeller. The liquid exerts a torque on the driven unit through these stationary guide vanes as it flows from pump to turbine runner.