RRB JE ME (CBT II) Mock Test- 3

1. Pack method

2. Cyaniding

3. Nitriding

4. Induction Hardening

5. Flame hardening

Important Points

Heat treatment is an operation involving heating and cooling of a metal or alloy so as to obtain the ,,certain desirable properties. A few important heat treatment processes are:

1. Annealing

2. Normalising

3. Hardening

4. Tempering

Concept:

Time of flight: t =

Maximum height: H =

Horizontal Range: R =

When θ = 45°: R_max =

The range of a projectile is maximum, when the angle of projection is 45°.

Calculation:

R_max = R/sin2θ = 15 / sin30^o = 3 km

Coating factor: The ratio of the coating diameter to the core wire diameter is called the coating factor.

• 1.25 to 1.3 for light coated

• 1.4 to 1.5 for medium coated

• 1.6 to 2.2 for heavy coated

• Above 2.2 for super heavy coated electrodes

Reynold Number

Where U is the average stream velocity and L is the characteristics length/width.

The hydraulic diameter which is used as the characteristic length in determination of friction factor, instead of ordinary geometrical diameter, is defined as

where A_w is the flow area and P_w is the wetted perimeter

Circular pipe of diameter d:

Important Points

Square duct of size a:

The rectangular duct of size a × b:

Concept:

The PERT (Project Evaluation and Review Technique) technique is used, when activity time estimates are stochastic in nature. For each activity, three values of time (optimistic, most likely, pessimistic) are estimated.

• Optimistic time (to) estimate is the shortest possible time required for the completion of the activity.
• The most likely time (tm) estimate is the time required for the completion of activity under normal circumstances.
• Pessimistic time (tp) estimate is the longest possible time required for the completion of the activity.

In PERT expected time of an activity is determined by using the below given formula:

Variance, σ2 =

Calculation:

From detritus, the chain proceeds to detritivores, then to carnivores, and finally to top carnivores.

We are aware that normally rainwater has a pH of 5.6. When the pH of the rainwater drops below 5.6, it is called acid rain.

Acid rain refers to the ways in which acid from the atmosphere is deposited on the earth’s surface. Oxides of nitrogen and sulphur which are acidic in nature can be blown by the wind along with solid particles in the atmosphere and finally settle down either on the ground as dry deposition or in water, fog and snow as wet deposition.

Acid rain is a byproduct of a variety of human activities that emit the oxides of sulphur and nitrogen in the atmosphere. As mentioned earlier, burning of fossil fuels (which contain sulphur and nitrogenous matter) such as coal and oil in power stations and furnaces or petrol and diesel in motor engines produce sulphur dioxide and nitrogen oxides.

SO₂ and NO₂ after oxidation and reaction with water are major contributors to acid rain because polluted air usually contains particulate matter that catalyses the oxidation.

2SO₂ (g) + O₂ (g) + 2H₂O (l) → 2H₂SO₄ (aq)

4NO₂ (g) + O₂ (g)+ 2H₂O (l) → 4HNO₃ (aq)

The bad effects of acid rain

• When acid rain falls and flows as groundwater to reach rivers, lakes etc, it affects plants and animal life in the aquatic ecosystem

• Acid rain is harmful to agriculture, trees,.. and plants as it dissolves and washes away nutrients needed for their growth.

• It causes respiratory ailments in human beings and animal

• It may also cause corrosion in many buildings bridges, monuments, fencing etc

• It causes irritation in the eyes and skin of human beings

• This rain reduces the lustre of the metals too

• Acid rain damages buildings and other structures made of stone or metal

• The Taj Mahal in India has been affected by acid rain

Important Points:

• The prescribed permissible noise level for silence zones is 50 and 40 decibels during daytime and night-time respectively

• The prescribed permissible noise level for the industrial area is 75 and 70 decibels during daytime and night-time respectively

• The prescribed permissible noise level for the residential area is 55 and 45 decibels during daytime and night-time respectively

• Delhi is the only union territory of India which has its own High court.

• It was established on 31 October 1966.

• The High Court of Delhi was established with Chief Justice KS Hegde, Justice ID Dua, Justice HR Khanna and Justice SK Kapur as the 4 judges.

• Chandigarh comes under the jurisdiction of Punjab and Haryana High Court.

• Puducherry comes under the jurisdiction of Madras High Court.

• Daman and Diu come under the jurisdiction of Bombay High Court.

• With the exit of Viral Acharya, the RBI rejigged portfolios of the other three deputy governors giving the important monetary policy and forecasting department to B P Kanungo.

• Now, all the other 3 deputy governors -- N S Vishwanathan, B P Kanungo and M K Jain have been made responsible for 12 departments each.

• Viral Acharya resigned in June 2019 as the deputy Governor of RBI.

The Result of a non-concurrent force system is the one which will have the same rotational and translatory effect as the given system of forces. It may be a single force, a pure moment of a force and a moment.

When a body is acted upon by a number of coplanar non-concurrent forces. A little consideration will show, that as a result of these forces, the body may have any one of the following states:

1. The body may move in any one direction.

2. The body may rotate about itself without moving.

3. The body may move in any one direction and at the same time, it may also rotate about itself.

4. The body may be completely at rest.

For Equilibrium of coplanar non-concurrent force system:

ΣF_x = 0

ΣF_y = 0

ΣM = 0

Municipal solid waste:

• Municipal solid waste (MSW) is more commonly known as trash or garbage

• It consists of everyday items we use and then throw away, such as product packaging, grass clippings, furniture, clothing, bottles, food scraps, newspapers, appliances, paint, and batteries.

• It is the non-hazardous solid waste

• It comes from our homes, schools, hospitals, and local councils

Important points:

There are different methods of solid waste management. The following are some of the recognized methods:

• Sanitary landfill

• Incineration

• Recovery and Recycling

• Composting

• The Dead Sea is a salt lake which is bordered by Jordan to the east and Israel to the west.

• The Dead Sea lies in the Jordan Rift Valley, with the Jordan River as its main tributary.

• Its surface and shores are 430.5 meters (1412 feet) below sea level.

Light rays from infinity, parallel to the principal axis, thus meet at the point on the principal axis on the side of the mirror, which is towards the object.

This distance is considered as negative.

Hence the focal length of a concave mirror is negative.

⇒ Focal length, f = R/2

⇒ f = 30/2 = 15 cm

For the Concave mirror, the focal length is negative.

Therefore, f = -15 cm.

KE gained = mgh

KE gained = 8*10*20

KE gained = 1600 J

KE = (1/2)mv²

1600 = (1/2)*8*v²

Solve for v

V = Square root of 400

V = 20 m/s²

The atmospheric refraction occurs in a medium of gradually changing refractive index.

Since the atmosphere bends starlight towards the normal, the apparent position of the star is slightly different from its actual position.

Most metal oxides are insoluble in water but some of these dissolve in water to form alkalis.

Sodium oxide and potassium oxide dissolve in water to produce alkalis as follows

Na₂O(s) + H₂O(l) → 2NaOH(aq)

K₂O(s) + H₂O(l) → 2KOH(aq)

Non-Metallic Oxides:

Most non-metals produce acidic oxides when dissolved in water

CO₂ + H₂O → H₂CO₃ (Carbonic acid)

SO­₃ + H₂O → H₂SO₄ (Sulphuric acid)

Edging: This applied to increase the cross-sectional area of the stock at the expense of its length.

Steel is an alloy of iron and carbon with a carbon content of up to a maximum of 2%.

Stainless steel contains Iron, Carbon, Chromium, and Nickel.

Stainless steels typically contain 10 - 30 % chromium besides other elements like C, Mn, Si, S, etc. Chromium imparts corrosion resistance to steel. Varying amounts of other alloying elements like Ni, Mo, V, Ti, Ni, etc., may be added to obtain certain specific properties.

According to Newton’s Second Law

The rate of change of momentum of an object is directly proportional to the resultant force applied and is in the direction of the resultant force.

Δ(mv) = F × Δt = 20 × 1 = 20 kg m/s

So, the longest path will represent the critical path for the network, and it will represent the minimum possible duration required to complete the project.

The critical path will be the longest path in the network requiring the maximum amount of time, but it will represent the minimum duration that is required to complete all the activities i.e. completion of a project.

• The internet is a globally connected network system that transmits data via various types of media. Sometimes it is referred to as a ‘network of networks’

• The World Wide Web, or simply the web, is a way of accessing information over the medium of the internet.

• A web browser is a software application for accessing the information on the World Wide Web.

When a body is loaded within an elastic limit, it changes its dimensions and on the removal of the load, it regains its original dimensions. So long as it remains loaded, it has stored energy in itself. On removing the load, the energy stored is given off, as in the case of a spring. This energy, which is absorbed in a body when strained within the elastic limit, is known as strain energy.

The strain energy stored in a body due to external loading, within the elastic limit, is known as resilience. The maximum energy stored in a body up to the elastic limit is called proof resilience.

The proof of resilience per unit volume of a material is known as the modulus of resilience.

Strain energy stored in a body due to tensile or compressive load or resilience:

Modulus of resilience:

Ductility is a measure of a material's ability to undergo significant plastic deformation before rupture, which may be expressed as percent elongation or percent area reduction from a tensile test.

In fatigue testing, the endurance limit i.e. the maximum stress which can be applied to a material for an infinite number of stress cycles without resulting in failure of the material is applied and measured.

Hardness is a characteristic of a material, not a fundamental physical property. It is defined as the resistance to indentation, and it is determined by measuring the permanent depth of the indentation. Hardness test is used to determine resistance to penetration.

A. Ductility ⇒ III. Tension Test

B. Endurance limit ⇒ II. Fatigue Test

C. Toughness ⇒ I. Impact Test

D. Resistance to penetration ⇒ IV. Hardness Test

• Kudremukh National park is located in Chikkamagaluru district of Karnataka.

• It was declared as a National Park in 1987.

• Other famous National parks in Karnataka are Bandipur, Nagarhole, and Anshi National Park.

• Famous National Parks in Kerala are Periyar, Silent Valley, and Anamudi Shola National Park.

• Famous National Parks in Tamil Nadu are Mudumalai, Mukurthi, and Indira Gandhi National Park.

• Famous National Parks in Odisha are Simlipal, and Bhitarkanika National park.

The temperature at which the structure of steel completely changes to AUSTENITE is called the upper critical temperature. This varies depending on the percentage of carbon in the steel.

• 0.57% and 1.15% carbon steel: In these cases, the lower critical temperature is 723°C and the upper critical temperature is 800°C.

• For 0.84% carbon steel, both lower critical temperature and upper critical temperature are 723°C. This steel is called eutectoid steel.

If steel is heated, a change in its structure commences from 723°C. The new structure formed is called ‘AUSTENITE’. Austenite is non-magnetic.

• If the hot steel is cooled slowly, the old structure is retained and it will have fine grains which makes it easily machinable.

• If the hot steel is cooled rapidly the austenite changes into a new structure called ‘MARTENSITE’. This structure is very fine-grained, very hard and magnetic. It is extremely wear-resistant and can cut other metals.

Methods of honing: Manual stroking and Power stroking

Manual stroking

• Manual stroking is preferred for large quantities when tolerances are extremely close.

• Many operators prefer this because of the flexibility in operation.

• This eliminates the use of expensive fixtures to hold the work.

• Jobs can be quickly changed from one type to another. Jobs can be reversed from end to end for accurate honing and correction.

• The stroke length can be altered depending on the actual requirement of the individual workpiece.

Power stroking

• Power stroking is used for honing all types of workpieces. Power stroking may prove to be economical particularly in the case of small parts.

Note

• Sometimes for final finishing, manual stroking is employed after power stroking.

Magnifications of 2000 times are quite common, and some may have as high as 40,000.

If a comparator has a magnification of 1000 and if the difference between the standard and actual dimensions of a work piece is 0.02 mm, it will result in pointer movement of 20 mm on the dial or the recording device of the comparator.

• In mechanical comparators, the magnification ranges from about 250 to 5000. These comparators are relatively cheap and are used mainly for comparative measurement of external surfaces.

• With an electrical comparator, magnifications of the order of 40000 or higher are obtainable.

• With a Pneumatic comparator, the magnification factor will vary from 1000 to 5000.

ν = 1.25 × 10^-4 m²/sec

ν = 1.25 cm²/sec

ν = 1.25 stokes

• Biswa Bhusan Harichandan took charge as new Governor of Andhra Pradesh in Rajbhavan in Vijayawada, Andhra Pradesh.

• His oath was administered by the AP High Court Acting Chief Justice Justice C. Praveen Kumar.

Facing:

• Facing is an operation of machining the ends of a workpiece to produce a flat surface square with the axis

• Drilling is the production of cylindrical holes of definite diameters in workpieces by using a multi-point cutting tool called a ‘drill’. It is the first operation done internally for any further operation.
• A reamer is a multi-point cutting tool used for enlarging by finishing previously drilled holes to accurate sizes.
• Knurling is the operation of producing a straight lined, diamond-shaped pattern or cross lined pattern on a cylindrical external surface by pressing a tool called a knurling tool. Knurling is not a cutting operation but it is a forming operation. Knurling is done at a slow spindle speed (1/3 the turning speed). However, the the speed & feed given for knurling is divided according to the job material and the finish required.

Purpose of knurling

• A good grip and make for positive handling
• Good appearance
• For raising the diameter to a small range for assembly to get a press fit

• The maximum load which the specimen can withstand without failure is called the load at the ultimate strength.
• Beyond point E, the cross-sectional area of the specimen begins to reduce rapidly over a relatively small length of the bar, and the bar is said to form a neck.
• This necking takes place while the load reduces, and fracture of the bar finally occurs at point F
• Owing to the large reduction in the area produced by the necking process the actual stress at fracture is often greater than the above value

Thermal Stress:

? = ?△TE ⇒ 12 x 10^-6 x (150 - 30) x E = 288

E = 0.2 x 10⁶MP? = 200GP?

• The Indian National Congress was formed under the tenure of Lord Dufferin in 1885.

• Lord Mayo was responsible for carrying out the census in the Indian History and was the first Governor-General to be murdered in his office.

• Lord Dalhousie introduced the Doctrine of Lapse, Postal services and Railways in India.

• Lord Cornwallis introduced the permanent settlement in Bengal and was also known as the Father of Civil services in India.

Lead time (L) is the time between placing and receiving an order

Reorder point = daily demand × lead time + safety stock

Important Points

• Safety stock is the buffer and is defined as the difference between the reorder level and the lead time demand. It is the buffer that we have to make sure that demand that exceeds the lead time demand is met during lead time.
• The safety stock or buffer stock function concerns short range variation in either demand or replacement. A great deal of inventory planning is devoted to determining the size of safety stocks. Safety stock provides protection against two types of uncertainty with sales in excess of forecast during the replenishment period. The second type of uncertainty concerns delays in replenishment.
• The reorder point is the inventory level at which a new order is placed. The order must be placed while there is enough stock in place to cover demand during lead time.
• The inventory level might be depleted at a slower or faster rate during lead time. When demand is uncertain, safety stock is added as a hedge against stock-out

Drilling: Operation of making a circular hole by removing a volume of metal from the job by a rotating cutting tool called drill

Boring: Process of enlarging a hole.

Reaming: Operation of finishing a drilled hole.

Counterboring: Operation of boring a second hole, larger in diameter than the first, but concentric with it.

The operation is performed in a vacuum to prevent the reduction of electron velocity.

It allows fusion welds of great depth with a minimum width because the beam can be focused and magnified.

Metals: Iron, lead, gold, aluminium, platinum, uranium, zinc, lithium, sodium, tin, silver, etc.

Non-Metals: Hydrogen, helium, carbon, sulphur, nitrogen, oxygen, radon, neon, other halogens, and noble gases etc.

Sulphur, a non-metal, is not lustrous.

Welding current is the most influential variable as it controls electrode melting rate, depth of penetration and the amount of base metal fused. However, very high current shall lead to too much penetration resulting in burn through in the metal being joined, excessive reinforcement and increased weld shrinkage and, therefore, a large amount of distortion. On the other hand, low current shall lead to insufficient penetration, lack of fusion and unstable arc.

If the welding speed is increased, power or heat input per unit length of the weld is decreased, less welding material is applied per unit length of the weld, and consequently less weld reinforcement results and penetration decreases. Travel speed is used primarily to control bead size and penetration. It is interdependent with the current.

Excessive high travel speed decreases wetting action, increases the tendency for undercut, arc blow, porosity and uneven bead shapes while slower travel speed reduces the tendency to porosity and slag inclusion.

• Too low welding current in arc welding would result in excessive piling up of weld metal
• Too high welding current in arc welding would result in excessive spatter
• Too fast welding speed in arc welding would result in the too small bead

• Each worksheet is made up of cells and cells are a result of the intersection of rows and columns

• They are basic units for storing data

• Each cell gets its name from this intersection

• The address of a cell that is in column A and has its row number as 4 is referred to as cell A4

• Thus the letter and number of the intersecting column and row is the cell address

• A group of contiguous cells is called a range

• An example of a cell range would be G1: G3

Balancing Oxygen:

LHS = 2

RHS = 3

LCM (2,3) = 6

Multiply Oxygen on LHS by 3 and on RHS by 2

a Fe + 3 O₂ + → 2 Fe₂O₃

Balancing Fe:

RHS = 4

LHS = 1

Multiply Fe on LHS by 4

4 Fe + 3 O₂ + → 2 Fe₂O₃

The different methods of taper turning on a lathe are:

• Form tool method

• Compound slide method

• Tailstock offset method

• Taper turning attachment method

Strength: Measure of the resistance of material to permanent deformation

Ductility: Measure of the degree of plastic deformation

Hardness: Resistance to localized deformation

Creep: Resistance to time dependent deformation under load

Fatigue: Resistance of a material against fluctuating stresses.

Fracture toughness: Resistance to brittle failure

The resultant force, of a given system of forces, may also be found out by the following laws:

1. Triangle law of forces.

2. Polygon law of forces.

Triangle Law of Forces

It states, “If two forces acting simultaneously on a particle, are represented in magnitude and direction by the two sides of a triangle, taken in order; their resultant may be represented in magnitude and direction by the third side of the triangle, taken in the opposite order.”

Polygon Law of Forces

It is an extension of Triangle Law of Forces for more than two forces, which states, “If a number of forces acting simultaneously on a particle, be represented in magnitude and direction, by the sides of a polygon taken in order; then the resultant of all these forces may be represented, in magnitude and direction, by the closing side of the polygon, taken in the opposite order.”

• Friction Welding: In this process, the heat for welding is obtained from mechanically induced sliding motion between rubbing surfaces of workpieces. Friction welded parts are used as a product for aerospace, agriculture, automotive, defense, marine and oil industries.

• TIG welding (Gas Tungsten Arc Welding) is used for welding ferrous metals, stainless steel, aluminum and thin sheet metal welding.

• Plasma Arc welding is also used to join thin sheet metals.

• Laser Welding is a method in which a work piece is melted and joined by a narrow beam of intense Monochromatic Light. (Laser Beam) When the beam strikes the job, the heat produced melts and fuses even the hardest materials. Laser Welding is used in the Space, Aircraft, Electronics industries for thinner section metals and dissimilar metals.

• Thermit welding is used for joining thick, heavy, irregularly shaped rods, like rails, etc. using a chemical heating process.

Pressure intensity inside a soap bubble,

p = 4? /r

? = pr/4 = 25 x 25 x 10^-¾

= 0.15625 N/m

Difference in pressure

= x 0.5

= 6.3 m

The specific volume on mass basis= 0.5/1 = 0.5 m³/kg

specific volume on mole basis= 0.5/(1/0.032) = 0.0160 m³/mole.

Anemometer: It is a device for measuring wind speed, and it is a common weather station instrument.

Orifice plate: It is a device used for measuring the volumetric flow. It uses Bernoulli's principle.

(i) absorb the pressure wave due to sudden blockage of flow in the turbine which will reduce water pressured hammer problem

(ii) to serve for emergency supply and to maintain constant head at inlet of the turbine

(a) constant rate of discharge can be ensured

(b) power consumption can be reduced because it reduces friction losses.

= 0.1cm water*1.9*1.1 = 2050 N.

= 200 × 10^(−4) × 5/0.001001 = 99.9 kg.

A. Work done in a polytropic process :

B. Work done in a steady flow process : ∫C dp

C. heat transfer in a reversible adiabatic process : zero

D. Work done is an isentropic process:

This is a case of a constant volume process or an isochoric process. In an irreversible constant volume process, the system doesn’t perform work on the surrounding at the expense of its normal energy. By performing work on the system, the temperature can be raised.

In T - S diagram

Process 1 - 2 → Isothermal process

Process 3 -1 → reversible adiabatic process

Thus, on the P-V diagram, the slope of the reversible adiabatic process

(3-1) is more than the slope of the isothermal process (1 - 2).

Process 2 - 3 → isobaric process line

T₁ = 606 + 273 = 879 K

T₂ = 20 + 273 = 293 K

n = T₁ - T,/T₁

= 879 - 293 / 879 = W/Q₁ (since W = 1 kW)

0.666 = 1/Q₁

Q₁ = 1.5 kW

Amount of heat rejected

Q₂ = Q₁ - W = 1.5 - 1.0 = 0.5 kW

From Clausius inequality

for reversible cycle

for irreversible cycle

∆P = ρ gH = gH/v = 9.80665 × 5/0.001001

= 48.98 kPa

P(total) = P(top) + ∆P = 149 kPa.

v = 1.3136 + (0.8689 – 1.3136)(140 − 100)/(150 – 100)

= 1.3136 + ( − 0.4447) × 0.8 = 0.9578 m³/kg.

Between 100 kPa and 200 kPa,

P = 100 + (200 – 100)(1.5 − 2.17226)/(1.08034 − 2.17226)

= 161.6 kPa.

Work ratio = net work / positive work = W_T - W_C / W_T

Propulsive efficiency is maximum when jet velocity (C_j) = forward velocity of aircraft (C_a)

Now thrust power = (C_j - C_a)C_a = 0

I.e. at maximum efficiency thrust power is zero.

1. Bell Coleman refrigeration: Expansion cylinder

2. Vapour compression refrigeration: compressor

3. Absorption refrigeration: Generator

4. Jet Refrigeration: Flash chamber

RSHF = RSH / RTH

RSH = 0.75 x 100 = 75 kW

RLH = 100 - 75 = 25 kW

RLH = 50 cmm (w₁ -w₂)

W₂ = 0.005kg/kg of dry air

n of diesel engine increases as the load on the engine decreases and at a limiting condition becomes Otto. With increase in load, the cut off ratio increases.

r_c = k/h = ⅕ = 20 cm

Thickness = 20 cm - 0.5 cm = 19.5 cm

Nusselt number = hL/k

100= h x 0.5/0.025

h = 5 W / M²K

m = 2n – 3

Truss contains a redundant member and is statically indeterminate

m > 2n - 3

The value of ultimate stress is always more than the breaking stress as formation of the neck (permanent deformation) requires more stress than to actually break.

μ = 0 to 0.5 (under uniaxial loading)

μ = 0 for cork

μ = 0.5 for perfectly plastic body (Rubber)

μ = .25 to 0.33 for steel

L = 2P – 4

Where, L = Number of links

P = Number of Pair

Relation between number of binary joints and number of links

2J = 3I -4

Where, J = Number of binary joint

L = Number of link

(i) If LHS > RHS – Locked Chain or frame or structure

(ii) If LHS = RHS – Kinematic Chain or Constrained Chain

(iii) If LHS < RHS – Unconstrained Chain

The Hooke’s joint or coupling is connected to two members A&B. ‘A’ is a static rod that rotates the ‘B’ rod. The ‘A’ rod rotation allows the rod to 'bend' in any direction and is commonly used in shafts that transmit ‘rotary motion’.

While in Brittle materials, stress concentration factor is important in both static and dynamic loading. Brittle materials fail due to fracture. So there is little deformation to relax the concentrated stresses and thus has damaging effects.

The process employs currents of the order of few KA, voltages range from 2 to 12 volts and times vary from few milliseconds to few seconds.

To avoid aspiration, the tapered sprues are designed in the gating systems. A sprue tapered to a smaller size at its bottom will create a choke which will help keep the sprue full of molten metal.