What is the value of darcy friction factor

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Reference no: EM13974665

1. A metallic rod of 500 mm length and 50 mm diameter, when subjected to a tensile force of 100 kN at the ends, experiences an increase in its length by 0.5 mm and a reduction in its diameter by 0.015 mm. The Poisson's ratio of the rod material is ___?

2. Critical damping is the

(A) largest amount of damping for which no oscillation occurs in free vibration
(B) smallest amount of damping for which no oscillation occurs in free vibration
(C) largest amount of damping for which the motion is simple harmonic in free vibration
(D) smallest amount of damping for which the motion is simple harmonic in free vibration

3. A circular object of radius r rolls without slipping on a horizontal level floor with the center having velocity V. The velocity at the point of contact between the object and the floor is

(A) zero

(B) V in the direction of motion

(D) V vertically upward from the floor

4. For the given statements:

I. Mating spur gear teeth is an example of higher pair
II. A revolute joint is an example of lower pair

Indicate the correct answer.
(A) Both I and II are false

(B) I is true and II is false

(D) Both I and II are true

5. Biot number signifies the ratio of

(A) convective resistance in the fluid to conductive resistance in the solid
(B) conductive resistance in the solid to convective resistance in the fluid
(C) inertia force to viscous force in the fluid
(D) buoyancy force to viscous force in the fluid

6. The maximum theoretical work obtainable, when a system interacts to equilibrium with a reference environment, is called

(A) Entropy (B) Enthalpy (C) Exergy (D) Rothalpy

7. For a completely submerged body with centre of gravity ‘G' and centre of buoyancy ‘B', the condition of stability will be

(A) G is located below B

(B) G is located above B

(D) independent of the locations of G and B

8. In a power plant, water (density = 1000 kg/m3) is pumped from 80 kPa to 3 MPa. The pump has an isentropic efficiency of 0.85. Assuming that the temperature of the water remains the same, the specific work (in kJ/kg) supplied to the pump is

(A) 0.34 (B) 2.48 (C) 2.92 (D) 3.43

9. Which one of the following is a CFC refrigerant?

(A) R744

(B) R290

(C) R502

(D) R718

9. The jobs arrive at a facility, for service, in a random manner. The probability distribution of number of arrivals of jobs in a fixed time interval is

(A) Normal (B) Poisson (C) Erlang (D) Beta

10. In exponential smoothening method, which one of the following is true?

(A) 0 Ç a Ç 1 and high value of a is used for stable demand
(B) 0 Ç a Ç 1 and high value of a is used for unstable demand
(C) a Ç 1 and high value of a is used for stable demand
(D) a Ç 0 and high value of a is used for unstable demand

11. For machining a rectangular island represented by coordinates P(0,0), Q(100,0), R(100,50) and S(0,50) on a casting using CNC milling machine, an end mill with a diameter of 16 mm is used.
The trajectory of the cutter centre to machine the island PQRS is

(A) (-8, -8), (108, -8), (108,58), (-8,58) , (-8, -8)
(B) (8,8), (94,8), (94,44), (8,44), (8,8)
(C) (-8,8), (94,0), (94,44), (8,44), (-8,8)
(D) (0,0), (100,0), (100,50), (50,0), (0,0)

12. Which one of the following instruments is widely used to check and calibrate geometric features of machine tools during their assembly?

(A) Ultrasonic probe

(B) Coordinate Measuring Machine (CMM)

(D) Vernier calipers

13. The major difficulty during welding of aluminium is due to its

(A) high tendency of oxidation

(B) high thermal conductivity

(D) low density

14. The main cutting force acting on a tool during the turning (orthogonal cutting) operation of a metal is 400 N. The turning was performed using 2 mm depth of cut and 0.1 mm/rev feed rate. The specific cutting pressure (in N/mm2) is

(A) 1000

(B) 2000

(C) 3000

(D) 4000

15. The process of reheating the martensitic steel to reduce its brittleness without any significant loss in its hardness is

(A) normalising (B) annealing (C) quenching (D) tempering

16. In solid-state welding, the contamination layers between the surfaces to be welded are removed by

(A) alcohol

(D) sand blasting

17. A pair of spur gears with module 5 mm and a center distance of 450 mm is used for a speed reduction of 5:1. The number of teeth on pinion is___.

18. Consider a cantilever beam, having negligible mass and uniform flexural rigidity, with length 0.01 m. The frequency of vibration of the beam, with a 0.5 kg mass attached at the free tip, is 100 Hz. The flexural rigidity (in N.m2) of the beam is___.

19. 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____

20. A block weighing 200 N is in contact with a level plane whose coefficients of static and kinetic friction are 0.4 and 0.2, respectively. The block is acted upon by a horizontal force (in newton) P=10t, where t denotes the time in seconds. The velocity (in m/s) of the block attained after 10 seconds is_______.

21. A slider crank mechanism has slider mass of 10 kg, stroke of 0.2 m and rotates with a uniform angular velocity of 10 rad/s. The primary inertia forces of the slider are partially balanced by a revolving mass of 6 kg at the crank, placed at a distance equal to crank radius. Neglect the mass of connecting rod and crank. When the crank angle (with respect to slider axis) is 30°, the unbalanced force (in newton) normal to the slider axis is____

22. A hydrodynamic journal bearing is subject to 2000 N load at a rotational speed of 2000 rpm. Both bearing bore diameter and length are 40 mm. If radial clearance is 20 µm and bearing is lubricated with an oil having viscosity 0.03 Pa.s, the Sommerfeld number of the bearing is____

23. A 200 mm long, stress free rod at room temperature is held between two immovable rigid walls. The temperature of the rod is uniformly raised by 250°C. If the Young's modulus and coefficient of thermal expansion are 200 GPa and 1×10-5 /°C, respectively, the magnitude of the longitudinal stress (in MPa) developed in the rod is___

24. 1.5 kg of water is in saturated liquid state at 2 bar (vf = 0.001061 m3/kg, uf = 504.0 kJ/kg, hf = 505 kJ/kg). Heat is added in a constant pressure process till the temperature of water reaches 400°C (v = 1.5493 m3/kg, u = 2967.0 kJ/kg, h = 3277.0 kJ/kg). The heat added (in kJ) in the process is____

25. Water flows through a pipe having an inner radius of 10 mm at the rate of 36 kg/hr at 25°C. The viscosity of water at 25°C is 0.001 kg/m.s. The Reynolds number of the flow is

26. For a fully developed flow of water in a pipe having diameter 10 cm, velocity 0.1 m/s and kinematic viscosity 10-5 m2/s, the value of Darcy friction factor is____

27. In a simple concentric shaft-bearing arrangement, the lubricant flows in the 2 mm gap between the shaft and the bearing. The flow may be assumed to be a plane Couette flow with zero pressure gradient. The diameter of the shaft is 100 mm and its tangential speed is 10 m/s. The dynamic viscosity of the lubricant is 0.1 kg/m.s. The frictional resisting force (in newton) per 100 mm length of the bearing is

28. In an air-standard Otto cycle, air is supplied at 0.1 MPa and 308 K. The ratio of the specific heats (μ) and the specific gas constant (R) of air are 1.4 and 288.8 J/kg.K, respectively. If the compression ratio is 8 and the maximum temperature in the cycle is 2660 K, the heat (in kJ/kg) supplied to the engine is____

29. A reversible heat engine receives 2 kJ of heat from a reservoir at 1000 K and a certain amount of heat from a reservoir at 800 K. It rejects 1 kJ of heat to a reservoir at 400 K. The net work output (in kJ) of the cycle is

(A) 0.8 (B) 1.0 (C) 1.4 (D) 2.0

30. An ideal reheat Rankine cycle operates between the pressure limits of 10 kPa and 8 MPa, with reheat being done at 4 MPa. The temperature of steam at the inlets of both turbines is 500°C and the enthalpy of steam is 3185 kJ/kg at the exit of the high pressure turbine and 2247 kJ/kg at the exit of low pressure turbine. The enthalpy of water at the exit from the pump is 191 kJ/kg. Use the following table for relevant data.

Superheated steam temperature (°C)

Pressure (MPa)

(m3/kg)

(kJ/kg)

(kJ/kg.K)

500

0.08644

3446

7.0922

500

0.04177

3399

6.7266

Reference no: EM13974665

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