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RRB JE ME CBT 2 Full Test 1 - Railways MCQ


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150 Questions MCQ Test RRB JE (Railways Junior Engineer) CBT Mock Test Series 2024 - RRB JE ME CBT 2 Full Test 1

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RRB JE ME CBT 2 Full Test 1 - Question 1

Work done is zero for the following process

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 1

For constant volume process
W = ∫PdV
Since
dV = 0
so W = 0 for constant volume process.
For free expansion work done is zero. W = 0
The process in which high-pressure fluid is converted to low pressure by using a throttle valve is Throttling. In the throttling process enthalpy remains constant, work done is zero.

RRB JE ME CBT 2 Full Test 1 - Question 2

In a reversible adiabatic process the ration  is equal to:

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 2

Relationship between P - V - T for a reversible adiabatic process:

RRB JE ME CBT 2 Full Test 1 - Question 3

Which of the following engine can be associated with heterogeneous combustion?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 3

IC Engines may be classified based on the state of air-fuel mixture present at the time of ignition in the engine cycle, the type of ignition employed and the nature of combustion process after ignition of the air-fuel mixture.

Physical State of Mixture

  • Homogeneous Charge:
    • Premixed outside (conventional gasoline and gas engines with fuel inducted in the intake manifold)
    • Premixed in-cylinder: In- cylinder direct injection and port fuel injection
  • Heterogeneous Charge (Diesel Engine)

Ignition Type

  • Positive source of Ignition e.g., spark ignition
  • Compression ignition

Mode of Combustion

  • Flame propagation
  • Spray combustion

The combustion process in a diesel engine is heterogeneous—that is, the fuel and air are not premixed prior to initiation of combustion. Because of heterogeneous material low speed and low pressure is generated as compared to SI engine where homogenous mixture of fuel is used

RRB JE ME CBT 2 Full Test 1 - Question 4

A frictionless heat engine can be 100% efficient only if the exhaust temperature is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 4


Efficiency of a Reversible Heat Engine:

η = 1 when TL = 0 for any TH
A heat engine can work on 100% efficiency when there is only heat input and no heat loss.
As W = QH – QL
All the heat supplied will be used in producing the work and there will be no losses.
All the temperature scale is taken in Kelvin.

RRB JE ME CBT 2 Full Test 1 - Question 5

In an Otto cycle, the heat addition and heat rejection take place at

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 5

Otto cycle: It is the standard air cycle used in the spark ignition (SI) engines or petrol engines.

Different processes of the Otto cycle are as follows:
Process 1-2: Isentropic compression
Process 2-3: Constant volume heat addition
Process 3-4: Isentropic expansion
Process 4-1: Constant volume heat rejection. 

RRB JE ME CBT 2 Full Test 1 - Question 6

The rate of heat transfer through a hollow cylinder of inner and outer radii r1 and r2, respectively, depends on

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 6

For hollow cylinder:


The rate of heat transfer through a hollow cylinder of inner and outer radii r1 and r2, respectively, depends on ratio of radii (r2/r1).

Note:

RRB JE ME CBT 2 Full Test 1 - Question 7

Which of the following quantity is not a property of a system?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 7

Any identifiable/observable characteristic of a system by which the physical condition of the system may be described is called property of the system.

Some familiar properties are pressure, temperature, volume and mass.

Properties may be divided into two categories i.e. extensive (dependent of mass) and intensive (independent of mass) properties.

RRB JE ME CBT 2 Full Test 1 - Question 8

In a closed system, a gas undergoes a quasi-equilibrium process as per the law P = (-4V + 10) N.m2 and the volume of the gas, V changes from 1 m3 to 2 m3. The work done will be

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 8


As W is positive to it is work output.

Note:

  • Work done on the system is negative
  • Work done by the system is positive
RRB JE ME CBT 2 Full Test 1 - Question 9

Maximum work by an expansion of a gas in a closed system is possible when the process takes place at constant

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 9


As a work done is the area under the PV diagram represents work done which is maximum for isobaric (P = c) process.

RRB JE ME CBT 2 Full Test 1 - Question 10

An ideal air compressor cycle (with clearance) on p-v diagram can be represented by ________ processes.

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 10

In practical design of compressors, some clearance is required between the cylinder and piston to prevent hitting of piston to crown of the cylinder. A compressor cycle with clearance is consists of two adiabatic processes and two isobaric processes.

RRB JE ME CBT 2 Full Test 1 - Question 11

Polytropic index n is given

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 11


RRB JE ME CBT 2 Full Test 1 - Question 12

The rate of radiation of a black body at 0°C is E J/sec. The rate of radiation of this black body at 273°C will be

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 12

The radiation energy emitted by a black body per unit time and per unit surface area is given by
Eb = σT4 (W/m2)
where Stefan – Boltzmann constant, σ = 5.67 × 10-8 W/m2 K4, T is absolute temperature of the surface in Kelvin.
Eb = Total emissive power of a black body
For a non-black surface having an emissivity ϵ, it follows that
Eb = ϵ σT4
Calculation:


E2 = 16 E1 = 16 E

RRB JE ME CBT 2 Full Test 1 - Question 13

Refrigeration is based on _________

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 13

Refrigeration is based on Clausius statement of second law of thermodynamics. This law states that it is impossible to develop a device which works on a cycle and transfers heat from lower temperature to higher temperature without any external energy input. On the other hand, heat engine works on the Kelvin Planck’s statement of second law of thermodynamics.

RRB JE ME CBT 2 Full Test 1 - Question 14

A Carnot cycle refrigerator operates between 250 K and 300 K. Its coefficient of performance is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 14



For Carnot cycle refrigeration:

RRB JE ME CBT 2 Full Test 1 - Question 15

A body subjected to coplanar non-concurrent forces will remain in a state of equilibrium if

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 15

Equations of equilibrium for Non-concurrent force System: A non-concurrent force systems will be in equilibrium if the resultant of all forces and moments is zero.

  • ΣFx = 0, ΣFy = 0 and ΣM = 0

Equations of equilibrium for concurrent force System: For the concurrent forces, the lines of action of all forces met at a point and hence the moment of those force about that point will be zero or ΣM = 0 automatically.

  • ΣFx = 0 and ΣFy = 0
RRB JE ME CBT 2 Full Test 1 - Question 16

The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 16

It has been observed that when a body, lying over another body, is gently pushed, it does not move because of the frictional force, which prevents the motion.

If the applied force exceeds this limit, the force of friction cannot balance it and the body begins to move, in the direction of the applied force. This maximum value of frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as limiting friction.

Static friction is the friction experienced by a body when it is at rest or it is the friction when the body tends to move.

RRB JE ME CBT 2 Full Test 1 - Question 17

The loss of kinetic energy, during inelastic impact of two bodies having masses m1 and m2, which are moving with velocity v1 and v2respectively, is given by

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 17
  • Momentum is conserved in all collisions.
  • In elastic collision, kinetic energy is also conserved.
  • In inelastic collision, kinetic energy is not conserved. In perfectly inelastic collision, objects stick together after collision.


Conservation of momentum:
m1v1 + m2v2 = (m1 + m2) vf

Kinetic energy before collision:

Kinetic energy after collision:



Change in kinetic energy:
 


 
Loss of kinetic energy:

RRB JE ME CBT 2 Full Test 1 - Question 18

Forces P, 3P, 2P and 5P act along the sides taken in order of a square. The magnitude of the resultant is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 18


ΣFx = 3P – 5P = -2P
ΣFx = P – 2P = -P
 

RRB JE ME CBT 2 Full Test 1 - Question 19

A block A is released from the top of smooth inclined plane and slides down the plane. Another block B is dropped from the same point and falls vertically downwards. Which one of the following statements will be true if the friction offered by air is negligible?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 19

Consider a block of mass m lying on a frictionless inclined plane of length AB = L, height = h and angle of inclination θ.

When the block is released, it moves down the plane under a force mg sin θ.
Hence the acceleration of the block down the plane is
a = g sin θ
If the block starts from rest from point A, then its velocity when it reaches the bottom B is given by
v2 – u2 = 2as
v2 – 0 = 2aL
 
For the block which falls vertically downward of height, h:

So, speed of both the blocks will be same.

RRB JE ME CBT 2 Full Test 1 - Question 20

Two circular discs have masses in the ratio 1 : 2 and radii in the ratio 2 : 1. The ratio of their moment of inertia about the diameter is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 20


Moment of inertia of a disc about its diameter:

Moment of inertia of a disc about its centre:

Calculation:

Two circular discs have masses in the ratio 1: 2 and radii in the ratio 2: 1. The ratio of their moment of inertia about the diameter is

RRB JE ME CBT 2 Full Test 1 - Question 21

A thin circular ring of mass 100 kg and radius 2 m resting on a smooth surface is subjected to a sudden application of a tangential force of 300 N at a point on its periphery. The angular acceleration of the ring will be

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 21


Consider a mass m rotating around an axis, a distance r away.
Newton’s second law: F = ma
We know a = αr
(a = tangential acceleration; α = angular acceleration)
F = ma = mrα
Calculation:
F = ma = m r α
300 = 100 × 2 × α
α = 1.5 rad/s2

RRB JE ME CBT 2 Full Test 1 - Question 22

Polar moment of inertia of an equilateral triangle of side ‘x’ is given by

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 22


Consider an isosceles triangle:

For an equilateral triangle:

 

RRB JE ME CBT 2 Full Test 1 - Question 23

If one of the walls moves in the direction of flow with uniform velocity while the other wall is stationary, then the resulting flow between parallel walls is called ______.

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 23

Couette flow is the flow of a viscous fluid in the space between two surfaces, one of which is moving tangentially relative to the other. The configuration often takes the form of two parallel plates or the gap between two concentric cylinders.

In plug flow, the velocity of the fluid is assumed to be constant across any cross-section of the pipe perpendicular to the axis of the pipe. The plug flow model assumes there is no boundary layer adjacent to the inner wall of the pipe.

Stokes flow or creeping flow is a type of fluid flow where advective inertial forces are small compared with viscous forces. The Reynolds number is low i.e. Re≪1. This is a typical situation in flows where the fluid velocities are very slow, the viscosities are very large.

RRB JE ME CBT 2 Full Test 1 - Question 24

The resultant upward pressure of the fluid on an immersed body is called

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 24

Buoyancy or upthrust, is an upward force exerted by a fluid that opposes the weight of an immersed object. Archimedes' Principle states that the magnitude of the buoyant force on an object is equal to the weight of the fluid it displaces.

RRB JE ME CBT 2 Full Test 1 - Question 25

Mercury is considered as a superior barometric fluid due to its

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 25

Barometer is used to determine the local atmospheric pressure.

Mercury is employed in the barometer because its density is sufficiently high for a relative short column to be obtained and also because it has very small vapour pressure at normal temperature. High density scales down the pressure head (h) to represent same magnitude of pressure in a tube of smaller height.

Considered a small diameter glass tube with mercury at normal temperature is inverted within a small tank of mercury, an equilibrium will be reached.

PB = ρgh + Pv

Pv is the pressure exerted on the free surface of the mercury within the glass tube.

The vapour pressure of mercury at normal temperature and atmospheric pressure is only 0.16 Pa while the quantity ρgh is equal to approximately 105 Pa i.e. an insignificant fraction can be neglected.

Due to its small vapour pressure mercury used to be the standard fluid for measuring absolute pressures.

RRB JE ME CBT 2 Full Test 1 - Question 26

The velocity of fluid particle at the centre of the pipe section is:

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 26


Velocity distribution of a flow of viscous fluid through circular pipe:

The velocity is maximum when r = 0 i.e. at the centre of pipe.

Average velocity:

RRB JE ME CBT 2 Full Test 1 - Question 27

The concept of stream function which is based on the principle of continuity is applicable to

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 27

It is defined as the scalar function of space and time, such that its partial derivative with respect to any direction gives the velocity component at right angles to that direction.

It is denoted by ψ and defined only for two-dimensional flow.

 

Properties of Stream function:

  • If stream function exists, it is a possible case of fluid flow which may be rotational or irrotational
  • If the stream function satisfies the Laplace equation i.e.  it is a case of irrotational flow

Recommended Similar Important Concept:

Velocity Potential Function:

It is defined as the scalar function of space and time, such that its negative derivative with respect to any direction gives the velocity in that direction.

It is denoted by ϕ and defined for two-dimensional as well as three-dimensional flow.

 

Properties of Stream function:

  • If velocity potential function exists, the flow should be irrotational
  • If the velocity potential function satisfies the Laplace equation i.e. it is a case of steady incompressible irrotational flow
RRB JE ME CBT 2 Full Test 1 - Question 28

 

All the terms of energy in Bernoulli’s equation  have dimension of

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 28

From the law of dimensional homogeneity, the constant must have the same dimensions as the other additive terms in the equation.
Thus P/γ and v2/2g will have same dimension as z i.e. Length.

All the terms of Bernoulli’s equation:

P/γ = P/ρg = Pressure energy per unit weight of fluid or pressure head
v2/2g = Kinetic energy per unit weight or kinetic head
z = Potential energy per unit weight or potential head

RRB JE ME CBT 2 Full Test 1 - Question 29

A reservoir containing water has two orifices of the same size at depths of 4 m and 9 m below the free surface of water. The ratio of discharges through these orifices is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 29



For same orifice at different height:
Q ∝ √h

RRB JE ME CBT 2 Full Test 1 - Question 30

Shear stress for a general fluid motion is represented by where n and A are constants. A Newtonian fluid is given by:

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 30



For Newtonian Fluid: A = 0 and n = 1 (Example: Air, Water, Glycerin)

For Bingham Plastic: A = τ0 and n = 1(Fluid does not move or deform till there is a critical stress. Example: Toothpaste)

For Dilatant: A = 0 and n > 1 (Fluid starts ‘thickening' with increase in its apparent viscosity. Example: starch or sand suspension or shear thickening fluid)

For Pseudo plastic: A = 0 and n < 1 (Fluid starts ‘thinning' with increase in its apparent viscosity. Example: Paint, polymer solutions, colloidal suspensions or shear thinning fluid)

RRB JE ME CBT 2 Full Test 1 - Question 31

The property of a fluid which determines its resistance to shearing stresses is called

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 31

Viscosity is a property of the fluid by which it offers resistance to shear or angular deformation.

Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible. It occurs at the interface of two liquids, due to the intermolecular force of cohesion.

Compressibility is the ability of fluid to change its volume under pressure.

RRB JE ME CBT 2 Full Test 1 - Question 32

The intensity of pressure at a point in a fluid is the same in all the directions, only when

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 32

According to Pascal’s Law, the pressure or intensity of pressure at a point in a static fluid is equal in all directions.

This law is valid for the cases of fluid flow where shear stresses do not exist. The cases are

  • Fluid at rest
  • No relative motion exists between different fluid layers. For example, fluid at a constant linear acceleration in a container
  • Ideal fluid flow where viscous force is negligible
RRB JE ME CBT 2 Full Test 1 - Question 33

In case of centrifugal pump, manometric head is proportional to

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 33

For a pump, the tangential velocity (u) and velocity of flow (Vf) are related to the manometric head (Hm) as
u ∝ Vf ∝ √Hm
u = πDN/60
⇒ √H∝ DN
Hm ∝ N2

RRB JE ME CBT 2 Full Test 1 - Question 34

The efficiency of a centrifugal pump is maximum when its blades are:

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 34

Backward curved vanes are commonly used (though the H-Q curve is declining) because these pumps operate at high efficiency than in case of forward curved vanes.

RRB JE ME CBT 2 Full Test 1 - Question 35

The size of the lathe is expressed as:

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 35

The size of a lathe machine is specified by the following points:-

  • The length of the bed
  • A maximum distance between live and dead
  • The height of centres from the bed
  • The swing diameter
  • The swing diameter over the bed – It refers to the largest diameter of the work that will be rotated without touching the bed
  • The swing diameter over carriage – It is the largest diameter of the work that will revolve over the saddle
  • The bore diameter of the spindle
  • Horsepower of the motor
RRB JE ME CBT 2 Full Test 1 - Question 36

Which one of them is not a suitable condition for producing continuous chip without BUE?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 36

Discontinuous Chip

  • Brittle work materials
  • Low cutting speeds
  • Large feed and depth of cut
  • Small rake angle
  • High tool-chip friction

Continuous Chip (Without BUE)

  • Ductile work materials
  • High cutting speeds
  • Small feeds and depths
  • Sharp cutting edge
  • Large rake angle
  • Low tool-chip friction

Continuous Chip (With BUE)

  • Ductile materials
  • Low-to-medium cutting speeds
  • Large feed
  • Small rake angle
  • Tool-chip friction causes portions of a chip to adhere to rake face
  • Built up Edge (BUE) forms, then breaks off, cyclically
RRB JE ME CBT 2 Full Test 1 - Question 37

In a turning tool, crater wear occurs on _______.

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 37

Crater wear occurs on the rake face. For crater, the wear temperature is the main culprit and tool diffuse into the chip material and tool temperature is maximum at some distance from the tooltip. So crater wear starts at some distance from the tool tip.

RRB JE ME CBT 2 Full Test 1 - Question 38

What is the coolant used for machining cast iron?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 38

The reason why you can machine cast iron without using coolants is that the graphite in the cast iron acts as a lubricant in itself. So it is generally dry for its self-lubricating property.

Machining of some materials like grey cast iron become inconvenient or difficult if any cutting fluid is employed in liquid form. In such a case, the only air blast is recommended for cooling and cleaning.

RRB JE ME CBT 2 Full Test 1 - Question 39

Facing operation is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 39

Facing is a machining operation by which the end surface of the workpiece is made flat by removing metal from it.
Undercutting/Grooving is the process of reducing the diameter of a workpiece over a narrow surface.
Knurling is an operation of embossing a diamond-shaped pattern on the surface of a workpiece.
Chamfering is the operation of bevelling the extreme end of a workpiece. It is used to remove the sharp edge of the workpiece surface.

RRB JE ME CBT 2 Full Test 1 - Question 40

A tool used in cutting an external thread is called a:

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 40

A tap cuts or forms a thread on the inside surface of a hole, creating a female surface which functions like a nut.

A die cuts an external thread on cylindrical material, such as a rod, which creates a male threaded piece which functions like a bolt.

Twist drill is a rotating cutting tool, used for cutting holes in rigid materials.

End mills are tools which have cutting teeth at one end, as well as on the sides, they are used for a variety of things including facing an edge and cutting slots or channels. A drill bit can only cut in the axial direction, but a milling bit can generally cut in all directions.

RRB JE ME CBT 2 Full Test 1 - Question 41

The grooving is an operation of:

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 41

Undercutting/Grooving is the process of reducing the diameter of a workpiece over a narrow surface.

Chamfering is the operation of bevelling the extreme end of a workpiece. It is used to remove the sharp edge of the workpiece surface.

Drilling is an operation of making a hole in the workpiece.

Reaming is an operation of finishing the previously drilled hole.

Boring is an operation of enlarging a hole already made in a workpiece.

Counter-boring is an operation of enlarging the end of the pre-existing drilled hole cylindrically.

Facing is a machining operation by which the end surface of the workpiece is made flat by removing metal from it.

Knurling is an operation of embossing a diamond-shaped pattern on the surface of a workpiece.

RRB JE ME CBT 2 Full Test 1 - Question 42

In which of the following operations performed on lathe machine, chips do not occur?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 42

Knurling: Knurling is a manufacturing process whereby a visually‐attractive diamond‐shaped (crisscross) pattern is cut or rolled into metal. This pattern allows human hands or fingers to get a better grip on the knurled object that would be provided by the originally‐smooth metal surface.

Boring: Boring always involves the enlarging of an existing hole, which may have been made by a drill or may be the result of a core in a casting.

Reaming: Reaming removes a small amount of material from the surface of holes. It is done for two purposes: to bring holes to a more exact size and to improve the finish of an existing hole.

Threading: It is the process of making internal or external threads on the workpiece.

Out of the above four processes except knurling, all other involves the chips. So Knurling is the right option.

RRB JE ME CBT 2 Full Test 1 - Question 43

Kitchen utensils are made using:

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 43


 

For kitchen utensils like cup shape components & hollow components the method followed is deep drawing.

What is Deep drawing?
Cup drawing or deep drawing is one of the widely used sheets metal forming operations. Cup-shaped objects, utensils, pressure vessels, gas cylinders, cans, shells, kitchen sink sets are some of the products of deep drawing. In this process, a sheet metal called blank is placed on a die cavity, held in position using a holding plate or holding ring and pressed against the die cavity using a solid punch. The sheet metal attains the shape of the die cavity with a flat bottom.

RRB JE ME CBT 2 Full Test 1 - Question 44

What is the major problem in hot extrusion?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 44

Hot extrusion consists of heating suitable metals and alloys to the proper temperature and placing the heated stock in the cylinder of an extruding press. The pressure obtained by a moving ram or piston forces the plastic metal through a die of specified shape.

One of the major problems in hot extrusion is the effect of hot metal on the equipment. Various methods are used to protect the dies. The die may be changed and allowed to cool for each piece.

RRB JE ME CBT 2 Full Test 1 - Question 45

The operation of finishing and sizing a hole produced by drilling and boring, is known as

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 45

The operation of finishing and sizing a hole produced by drilling and boring is known as reaming. Reaming removes a small amount of material from the surface of holes.

It is done for two purposes:
1. To give a more accurate size to the hole
2. To improve the finish of an existing hole
Chemfering: Chamfering is a finishing process to make a bevel, groove or furrow in the machined part.
Filing: Filing is a method of removing excess material from a workpiece by using a file.
Forming: It is the process of plastically deforming a metal part to get the desired shape. Some of the forming techniques are rolling, extrusion, forging etc.

RRB JE ME CBT 2 Full Test 1 - Question 46

Which of the following machines does not require quick return mechanism?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 46

A quick return mechanism is an apparatus that converts circular motion into reciprocating motion (repetitive back - and - forth linear motion).

This mechanism is mostly used in shaping, planning and slotting machines.

The broaching is a machining operation which uses a tool called broach moving it over the workpiece to remove material, cutting a predetermined shape. Commonly circular or odd shapes, both internal or external, are obtained by broaching.

RRB JE ME CBT 2 Full Test 1 - Question 47

The main cause of rough holes during drilling is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 47

The common defects in drilling are listed below:

RRB JE ME CBT 2 Full Test 1 - Question 48

_______ does not contain tin as an alloying element.

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 48

Babbitt metal contains Sn (Tin) = 88%, Sb (antimony) = 8%, Cu (copper) = 4%. It possesses excellent antifriction properties and sufficient mechanical strength, so most commonly used in bearing metal.

White Metal is an alloy of Antimony, Copper and Lead.

Solders are essentially alloys of lead and tin.

RRB JE ME CBT 2 Full Test 1 - Question 49

The property of a metal is said to be withstand scratching, wear, abrasion and penetration is called _______.

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 49

Mechanical properties of a metal:

RRB JE ME CBT 2 Full Test 1 - Question 50

The material of an engine block is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 50

Engine block or cylinder block is the base of the engine. Two types of cylinder blocks are used in the engine

  1. Single piece casting
  2. Two-piece casting

The cylinder block is made of cast iron or aluminium alloy. Inside the engine block, passage for coolant and lubricating oil are provided. 

RRB JE ME CBT 2 Full Test 1 - Question 51

_________Steel is widely used for rails of a railway track.

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 51


 

Low Carbon Steel:

  • Contain less than about 0.25 weight% of carbon (Mild Steel)
  • Relatively soft and weak
  • Outstanding ductility and toughness
  • High machinability and weldability
  • Used for Beams, Channels, Nuts, Bolts, Wires, Tin cans etc.


Medium carbon steel:

  • Contain 0.25 – 0.6 weight % of carbon
  • Stronger than low carbon steel but of low ductility and toughness
  • Good wear resistance
  • Used in Railway wheels and Railway tracks, Gears, Crankshafts etc.


High Carbon Steel:

  • Contain 0.6 – 1.4 weight% of Carbon
  • Hardest, strongest and least ductile carbon steel
  • Can be alloyed with carbon and other metals to form very hard and wear resistance materials
  • Used in Cutting tools, embossing dies, saws, concrete drills etc.
RRB JE ME CBT 2 Full Test 1 - Question 52

Shock resistance of steel is increased by adding

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 52

Effect of Chemical Elements in Steel

Chromium (Cr): Chromium is present in certain structural steels in small amounts. It is primarily used to increase the corrosion resistance of the material.

Nickel (Ni): In addition to its favorable effect on the corrosion resistance of steel, nickel enhances the low-temperature behavior of the material by improving the fracture toughness.

Shock resistance of steel is increased by adding Nickel.

RRB JE ME CBT 2 Full Test 1 - Question 53

The main purpose of annealing is _______.

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 53

Annealing refers to a wide group of heat treatment processes and is performed primarily for homogenization, recrystallization or relief of residual stress in typical cold worked or welded components.

The purpose of annealing is to:

  • Increase ductility
  • Induce softness
  • Reduce Hardness
  • Improve machinability
RRB JE ME CBT 2 Full Test 1 - Question 54

Cyaniding and Nitriding are the two methods of which of the following process?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 54

Case hardening is a method used to harden the outer surface of low-carbon steel while leaving the centre or core soft and ductile. Case hardening involves heating the metal to its critical temperature in some carbonaceous material. The following methods are commonly used:
1. Pack method
2. Cyaniding
3. Nitriding
4. Induction Hardening
5. Flame hardening

Heat treatment is an operation involving heating and cooling of a metal or alloy so as to obtain certain desirable properties. A few important heat treatment processes are:
1. Annealing
2. Normalising
3. Hardening
4. Tempering

RRB JE ME CBT 2 Full Test 1 - Question 55

In a thin cylindrical shell, the ratio of longitudinal stress to hoop stress is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 55

A thin pressure vessel having closed ends and contains a fluid under a gauge pressure ‘p’. Then the walls of the cylinder will have a longitudinal stress as well as a circumferential stress.
Circumferential or hoop stress: 
Longitudinal or axial stress: 
where ‘d’ is the internal diameter and ‘t’ is the wall thickness of the cylinder.
The ratio of longitudinal stress to hoop stress 

RRB JE ME CBT 2 Full Test 1 - Question 56

If W be the total weight of the bar hanging fixed at one end, then elongation (δL) will be equal to _____. L = Length of the bar, E = Young’s modulus of elasticity, A = Cross sectional area of uniform circular bar.

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 56

Elongation of a bar due to its own weight:

λ is specific weight or unit weight of the material (Weight per unit volume), N/m3

Wx = Weight of portion below the section = λ × Ax
Stress on the element, dx = Wx/A = λx
Strain in the element, ϵ = Stress/E = λx/E
Elongation of the element, δLx = Strain × Length of Element

Total elongation:

If W is total weight of the bar, W = λ × AL

RRB JE ME CBT 2 Full Test 1 - Question 57

When a cast iron specimen is subjected to a tensile test, then percentage reduction in area will be equal to

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 57

In Brittle materials under tension test undergoes brittle fracture i.e there failure plane is 90° to the axis of load and there is no elongation in the rod that’s why the diameter remains same before and after the load. Example: Cast Iron, concrete etc

But in case of ductile materials, material first elongate and then fail, their failure plane is 45° to the axis of the load. After failure cup-cone failure is seen. Example Mild steel, high tensile steel etc.

RRB JE ME CBT 2 Full Test 1 - Question 58

A circular rod of diameter ‘d’ and length 3d is subjected to a compressive force F acting at the top point as shown in figure. Then the stress value at bottom most support at point A.

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 58


 

Force F acting at the top point will produce an equivalent load F and moment (F × d/2) at the centre of cross section:


At centre:
Due to compressive load F ⇒ Compressive axial stress σa at A
Due to bending moment M ⇒ Tensile stress σm at A

RRB JE ME CBT 2 Full Test 1 - Question 59

Torsional rigidity of a solid circular shaft of diameter d is proportional to

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 59


Torque per radian twist is known as torsional stiffness (k)

The parameter GJ is called torsional rigidity of the shaft. 
Torsional rigidity is also defined as torque per unit angular twist.

Torsional rigidity of a solid circular shaft is proportional to d4.

RRB JE ME CBT 2 Full Test 1 - Question 60

Which of the following conditions is TRUE for the shafts connected in series to each other?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 60


Two shafts of different materials can be joined together is two ways:

Shafts in series:

  • Two shafts are said to be joined in series if the driving torque is applied at one end and the resisting torque at the other end
  • For shafts in series, both the shafts carry the same torque T and the total angle of twist at the resisting end is the sum of separate angles of twist of two shafts
  • T1 = T2

Shafts in parallel:

  • If two or more shafts are rigidly fixed together such that the applied torque is shared between them then the composite shaft so formed is said to be connected in parallel
  • Angle of twist for both the shafts is the same
  • θ1 = θand T = T1 + T2
RRB JE ME CBT 2 Full Test 1 - Question 61

A metallic cube is subjected to equal pressure (P) on its all the six faces. If ϵV is volumetric strain produced, the ratio P/ϵis called

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 61

When a body is subjected to the identical stress σ in three mutually perpendicular directions, the body undergoes uniform changes in three directions without the distortion of the shape.

The ratio of change in volume to original volume is defined as volumetric strain (ϵV).
Bulk modulus (K) 

RRB JE ME CBT 2 Full Test 1 - Question 62

Shear force at any point of the beam is the algebraic sum of

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 62

At any x-section of a beam, the shear force ‘F' is the algebraic sum of all the lateral components of the forces acting on either side of the x-section.

Bending moment is the algebraic sum of the moments about an x-section of all the forces acting on either side of the section.

RRB JE ME CBT 2 Full Test 1 - Question 63

The shear force obtained at the midpoint of the cantilever beam is 12 kN. What is the value of uniformly distributed load w (kN/m) acting over the entire length, if the span length of the beam is 4 m?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 63

Shear force at any section X-X is given by:

FX-X = wx
At x = 2m,
FX-X = 12kN
w × 2 = 12kN
w = 6 kN/m

RRB JE ME CBT 2 Full Test 1 - Question 64

Preheating of work piece is essential in welding

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 64

Preheating is often employed when welding cast iron, high carbon steel or alloy steel since preheating slows down the cooling rate of that area of parent metal close to the weld itself and the weld itself and thereby prevents the formation of martensite which accounts for hardness across the weld. The change of cracking in the heat-cooling is also minimized by preheating.

RRB JE ME CBT 2 Full Test 1 - Question 65

Fluxes are used in welding in order to protect the molten metal and surfaces to be joined from:

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 65

Introduction of welding flux
Flux is a fusible (easily melted) chemical compound to be applied before and during welding to prevent unwanted chemical action during welding and thus making the welding operation easier.

These substances remove oxides from the edges to be welded and controls the fluidity of the molten metal.

The function of flux in gas welding:

  • To dissolve oxides and to prevent impurities and other inclusion that could affect the weld quality
  • Fluxes help the flow of their metal into very small gap between the metals being joined
  • Fluxes act as cleaning agents to dissolve and remove oxides and clean the metal for welding from dirt and other impurities

Note: Primary function of flux is to protect the surface from oxidation so don’t confuse with option ‘Dirt’.

RRB JE ME CBT 2 Full Test 1 - Question 66

Submerged arc welding process is done with________

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 66
  • In submerged arc welding (SAW) the arc and weld zone are completely submerged under a blanket of granulated flux, instead of shielding gas
  • Granular flux provides shielding to the weld pool from atmospheric gases and control of weld metal composition through presence of alloying element in flux
  • A continuous wire electrode is fed into the weld
  • This is a common process for welding structural carbon or carbon-manganese steelwork
RRB JE ME CBT 2 Full Test 1 - Question 67

Oxy-acetylene welding is categorised in

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 67

Oxy‐fuel gas Welding (OFW):

  • In Oxy-fuel welding, the heat source is the flame produced by the combustion of fuel gas and oxygen
  • This welding technique has largely been replaced by other processes but it is still popular because of its portability and the low capital investment
  • Acetylene is the principal fuel gas employed
  • Three types of flames can be obtained by varying the oxygen/acetylene (or oxygen/fuel gas) ratio named oxidizing, reducing and neutral flame
RRB JE ME CBT 2 Full Test 1 - Question 68

Brazing is done at the temperature of ________

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 68

Both brazing and soldering are the metal joining processes in which parent metal does not melt but only filler metal melts filling the joint with capillary action.

  • If the filler metal is having melting temperature more than 450°C but lower than the melting temperature of components, then it is termed as process of brazing or hard soldering.
  • However, if the melting temperature of filler metal is lower than 450°C and lower than the melting point of the material of components then it is known as soldering or soft soldering.
RRB JE ME CBT 2 Full Test 1 - Question 69

The composition of soft solder is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 69
  • Soldering is the process by which metallic materials are joined with the help of another liquified metal (solder)
  • Soldering can be classed as soft soldering and hard soldering.
  • The process of joining metals using tin-lead solders which melt below 420°C is known as soft soldering
  • The process of joining metals using hard solders consisting of copper, zinc, cadmium and silver which melt above 600° is known as hard soldering
  • The eutectic alloy of tin-lead solder is a mixture of 63% tin and 37% lead. 63/37 solder melts at 183oC
RRB JE ME CBT 2 Full Test 1 - Question 70

A collimated light beam is used to produce heat in case of

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 70

Percussion welding (PEW) is a type of resistance welding that blends dissimilar metals together.

The plasma arc welding (PAW) can be considered as an advanced version of TIG welding. Like TIGW, PAW also uses the tungsten electrode and inert gases for shielding of the molten metal.

Tungsten Inert Gas (TIG) or Gas Tungsten Arc (GTA) welding is the arc welding process in which arc is generated between non-consumable tungsten electrode and workpiece. The tungsten electrode and the weld pool are shielded by an inert gas normally argon and helium.

Laser Welding is a method in which work piece is melted and joined by narrow beam of intense Monochromatic Light. (Laser Beam) When the beam strikes the job, the heat produced melts and fuses even the hardest materials.

∴ A collimated light beam is used to produce heat in case of LASER welding.

RRB JE ME CBT 2 Full Test 1 - Question 71

Which type of filler rod is used in gas welding of stainless steel?

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 71

Columbium stainless steel is used in gas welding of stainless steel.

Stainless steel

Stainless steel is an alloy of iron, chromium, and nickel. There are many different classifications of stainless steel according to the percentage of its alloying elements.

Pieces of wires or rods of standard diameter and length used as filler metal in the joint during gas welding process are called filler rods or welding rods.

Types of stainless-steel filler rods:

Specially treated stainless-steel filler rods, which contain stabilizing elements such as molybdenumcolumbium, zirconium, titanium etc., are available.

The chromium percentage is also sometimes 1 to 1.5 percent more than in the base metal, to compensate the losses that may occur during the welding operation from the base metal.

RRB JE ME CBT 2 Full Test 1 - Question 72

Arc blow is a welding defect which is encountered

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 72

Arc blow is basically a deflection of a welding arc from its intended path i.e. the axis of the electrode. Deflection of the arc during welding reduces the control over the handling of molten metal by making it difficult to apply the molten metal at right place. Arc blow is mainly encountered during DC arc with straight polarity welding due to an interaction between different electromagnetic fields in and around the welding arc.

Types of Arc blow:

  • Forward Arc Blow
  • Backward Arc Blow
RRB JE ME CBT 2 Full Test 1 - Question 73

The grinding wheel is considered better, if the grinding ratio is

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 73

Grinding ratio is defined as

The G ratio is a measure of grinding production and reflects the amount of work a wheel can do during its useful life.

G increases with less wheel wear and/or higher metal removal. The higher it is, the better the grinding conditions, especially in terms of longer wheel life.

RRB JE ME CBT 2 Full Test 1 - Question 74

In a grinding wheel designation given by, A 60 G 7 B 23, B stands for

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 74
  • V – VITRIFIED
  • S – SILICATE
  • R – RUBBER
  • RF – RUBBER REINFORCED
  • B – RESINOID (SYNTHETIC RESINS)
  • BF – RESINOID REINFORCED
  • E – SHELLAC
  • Mg – MAGNESIA

    In "A 60 G 7 B 23" B represents Resinoid bond.
RRB JE ME CBT 2 Full Test 1 - Question 75

Glazing in grinding wheels ________ cutting capacity.

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 75

Glazing: When a surface of the wheel develops a smooth and shining appearance, it is said to be glazed. This indicates that the wheel is blunt, i.e. the abrasive grains are not sharp.

  • Glazing is caused by grinding hard materials on a wheel that has too hard a grade of bond. The abrasive particles become dull owing to cutting the hard material. The bond is too firm to allow them to break out. The wheel loses its cutting efficiency.
  • Glazing of grinding wheel is more predominant in hard wheels with higher speeds. With softer wheels and relatively lower speeds, this effect is less prominent.
RRB JE ME CBT 2 Full Test 1 - Question 76

The silicon carbide abrasive is chiefly used for grinding

Detailed Solution for RRB JE ME CBT 2 Full Test 1 - Question 76

Grinding wheel is a multipoint cutting tool having abrasive particles bonded together and so forming a structure.

Generally abrasive properties like hardness, toughness and resistance to fracture uniformly abrasives are classified into two principal groups:

Natural abrasives: The natural abrasives are emery and corundum. These are impure forms of aluminium oxide.

Artificial abrasives: Artificial abrasives are silicon carbide and aluminium oxide.

  • Silicon Carbide: It is less hard than diamond and less tough than aluminium oxide. It is used for grinding of material of low tensile strength like cemented carbide, stone and ceramic, grey cast iron, copper, brass, bronze, aluminium, vulcanized rub