Past Year Paper - Mechanical Engineering GATE : 2020 (Session - 1)


65 Questions MCQ Test Mock Test Series - Mechanical Engineering (ME) for GATE 2020 | Past Year Paper - Mechanical Engineering GATE : 2020 (Session - 1)


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This mock test of Past Year Paper - Mechanical Engineering GATE : 2020 (Session - 1) for GATE helps you for every GATE entrance exam. This contains 65 Multiple Choice Questions for GATE Past Year Paper - Mechanical Engineering GATE : 2020 (Session - 1) (mcq) to study with solutions a complete question bank. The solved questions answers in this Past Year Paper - Mechanical Engineering GATE : 2020 (Session - 1) quiz give you a good mix of easy questions and tough questions. GATE students definitely take this Past Year Paper - Mechanical Engineering GATE : 2020 (Session - 1) exercise for a better result in the exam. You can find other Past Year Paper - Mechanical Engineering GATE : 2020 (Session - 1) extra questions, long questions & short questions for GATE on EduRev as well by searching above.
QUESTION: 1

He is known for his unscrupulous ways. He always sheds _______ tears to deceive people.

Solution:

The term crocodile tears refers to hyporite crying. It is a false or insincere display of grief.

QUESTION: 2

The bar graph shows the data of the students who appeared and passed in an examination for four schools P, Q, R and S. The average of success rates (in percentage) of these four schools is __________.​

Solution:

Average percentage of passing students = 

QUESTION: 3

Select the graph that schematically represents BOTH y = xm and y = x1/m properly in the interval 0 ≤ x ≤ 1. For integer values of m,  where m > 1.
 

Solution:
QUESTION: 4

Define [x ] as the greatest integer less than or equal to x, for each x ∈(–∞, ∞). If y = [x], then area under y for x ∈[1, 4] is _______.

Solution:


Area = 1 × 1 + 1 × 2 + 1 × 3
= 1 + 2 + 3 = 6

QUESTION: 5

P, Q, R and S are to be uniquely coded using α and β. If P is coded as αα and Q as αβ, then R and S, respectively, can be coded as ________.

Solution:

βα and ββ
Given,
code of P = αα
code of Q = αβ
these
code of R = βα
and
code of S = ββ

QUESTION: 6

Crowd funding deals with mobilisation of funds for a project from a large number of people, who would be willing to invest smaller amounts through web-based platforms in the project. Based on the above paragraph, which of the following is correct about crowd funding?

Solution:

Crowd funding has been defined as a large number of people making small cantribution for a project. Only option and is implied.

QUESTION: 7

Jofra Archer, the England fast bowler, is _______ than accurate.

Solution:

When two qualities of the same noun are compared, more + positive degree adjective is used. Use more fast and not ‘faster’.

QUESTION: 8

Select the word that fits the analogy:​
Build : Building : : Grow : _______

Solution:

Build : Building
(verb)  (noun)
Grow : Growth
(verb)   (noun)

QUESTION: 9

I do not think you know the case well enough to have opinions. Having said that, I agree with your other point. What does the phrase “having said that” mean in the given text?

Solution:
QUESTION: 10

The sum of the first n terms in the sequence 8, 88, 888, 8888, .... is ______.

Solution:

Using throw options put n = 1 and n = 2
Actual method:
8 + 88 + 888 + ......
8[1 + 11 + 111 + ......]

*Answer can only contain numeric values
QUESTION: 11

For three vectors whereare unit vectors along the axes of a right-handed rectangular/Cartesian coordinate system, the value of  is __________.


Solution:

+ 6 = 0 + 6 = 6

*Answer can only contain numeric values
QUESTION: 12

He compressor of a gas turbine plant, operating on an ideal intercooled Brayton cycle, accomplishes an overall compression ratio of 6 in a two-stage compression process, Intercooling is used to cool the air coming out from the first stage to the inlet temperature of the first stage, before its entry to the second stage. Air enters the compressor at 300 K and 100 kPa. If the properties of gas are constant, the intercooling pressure for minimum compressor work is________ kPa (round off to 2 decimal places).


Solution:

P3/P1 = 6  ⇒ P3 = 600 kPa
Intermediate pressure = 

QUESTION: 13

The Laplace transform of a function f (t) is L(f ) =  Then, f(t) is

Solution:

QUESTION: 14

Match the following.​

Solution:
QUESTION: 15

A single-degree-of-freedom oscillator is subjected to harmonic excitation F (t) = F0cos(ωt ) as shown in the figure.

The non-zero value of ω, for which the amplitude of the force transmitted to the ground will be F0, is

Solution:

Given,
FT = F0
Then transmissibility




Taking (–ve) sign
⇒ 
⇒ 
⇒ 

QUESTION: 16

For an ideal gas, the value of the Joule-Thomson coefficient is

Solution:

Value of Joule Thomson coefficient for ideal gas μ = 

QUESTION: 17

He stress state at a point in a material under plane stress condition is equi-biaxial tension with a magnitude of 10 MPa. If one unit on the σ – π plane is 1 MPa, the Mohr's circle representation of the state-of-stress is given by

Solution:

QUESTION: 18

The base of a brass bracket needs rough grinding. For this purpose, the most suitable grinding wheel grade specification is

Solution:

For brass ‘Silicon carbide’ is the abrasive. As brass is soft material, we need hard wheel.
Therefore ‘Q’ is the best choice.

So, ‘J ’ is in the softer side. So best option is (b).

QUESTION: 19

Which of the following function f (z), of the complex variable z , is NOT analytic at all the points of the complex plane?

Solution:

logz is not analytic at all points.

QUESTION: 20

Multiplication of real valued square matrices of same dimension is

Solution:

Matrix multiplication is associative.

*Answer can only contain numeric values
QUESTION: 21

A company is hiring to fill four managerial vacancies. The candidates are five men and three women. If every candidate is equally likely to be chosen then the probability that at least one women will be selected is _______ (round off to 2 decimal places).


Solution:

5 men, 3 women
P [atleast one women selected for 4 vacancies]
=1 – P [none]

*Answer can only contain numeric values
QUESTION: 22

In a concentric tube counter-flow heat exchanger, hot oil enters at 102°C and leaves at 65°C. Cold water enters at 25°C and leaves at 42°C. The log mean temperature difference (LMTD) is _______°C (round off to one decimal place).


Solution:

Thi = 102°C, The = 65°C
Tc,i = 25°C, Tce = 42°C

ΔT1 = 102°C – 42°C = 60°C;ΔT2 = 65°C – 25°C = 40°C;

*Answer can only contain numeric values
QUESTION: 23

A flywheel is attached to an engine to keep its rotational speed between 100 rad/s and 110 rad/s. If the energy fluctuation in the flywheel between these two speeds is 1.05 kJ then the moment of inertia of the flywheel is _________________kg.m2 (round off to 2 decimal places).


Solution:


∴ 1.05 × 103 × 2 = 
I = 1 kg.m2

QUESTION: 24

In the Critical Path Method (CPM), the cost-time slope of an activity is given by

Solution:
*Answer can only contain numeric values
QUESTION: 25

A sheet metal with a stock hardness of 250 HRC has to be sheared using a punch and a die having a clearance of 1 mm between them. If the stock hardness of the sheet metal increases to 400 HRC, the clearance between the punch and the die should be_________ mm.


Solution:

Tensile strength ∝ Hardness number
∴ Shear strength = 0.5 tensile strength (Tresca theory)
= 0.577 tensile strength (Von mises theory)
Shear strength ∝ Hardness number
and clearance, C = 0.0032t√τ


Or 

QUESTION: 26

For an ideal gas, a constant pressure line and a constant volume line intersect at a point, in the Temperature (T) versus specific entropy (s) diagram. CP is the specific heat at constant pressure and CV is the specific heat at constant volume. The ratio of the slopes of the constant pressure and constant volume lines at the point of intersection is

Solution:

If
v = C
Tds = du + pdv
Tds = du
du = CVdT   [∵ V = C]
Tds = CVdT

If P = C
Tds = dh – vdP
dh = CPdT  [∵ P = C]
Tds = CPdT

Ratio,

*Answer can only contain numeric values
QUESTION: 27

A balanced rigid disc mounted on a rigid rotor has four identical point masses, each of 10 grams, attached to four points on the 100 mm radius circle shown in the figure

The rotor is driven by a motor at uniform angular speed of 10 rad/s. If one of the masses gets detached then the magnitude of the resultant unbalance force on the rotor is ______ N. (round off to 2 decimal places).


Solution:


ω = 10 rad/s, r = 100 mm = 0.1 m
If one mass is detached then

Now, unbalance tone, F = mrω2

= 0.1 N

QUESTION: 28

A four bar mechanism is shown below.

For the mechanism to be a crank-rocker mechanism, the length of the link PQ can be

Solution:


For Crank-Rocker mechanism, shortest link must be crank and adjacent to fixed as well as Grashoff’s law must be satisfied.
If  l = 80 mm
then shortest  will be = 80 mm
as well as (80 + 600) < (400 + 300) 680 < 700
Therefore law is satisfied.
⇒ l = 80 mm

QUESTION: 29

The value of 

Solution:


Applying ‘L’ Hospital rule

QUESTION: 30

A helical gear with 20° pressure angle and 30° helix angle mounted at the mid-span of a shaft that is supported between two bearings at the ends. The nature of the stresses induced in the shaft is

Solution:
QUESTION: 31

The crystal structure of γ iron (austenite phase) is

Solution:
QUESTION: 32

The velocity field of an incompressible flow in a Cartesian system is represented by

Which one of the following expressions for v is valid?

Solution:


For Incompressible flow



v =– 4xy + f (x, z )

QUESTION: 33

Match the following non-dimensional numbers with the corresponding definitions:

Solution:
QUESTION: 34

The members carrying zero force (i.e. zero-force members) in the truss shown in the figure, for any load P > 0 with no appreciable deformation of the truss (i.e. with no appreciable change in angles between the members), are​

Solution:
QUESTION: 35

Froude number is the ratio of

Solution:
QUESTION: 36

A vector field is defined as

where,  are unit vectors along the axes of a right-handed rectangular/Cartesian coordinate system. The surface integral (where is an elemental surface areavector) evaluated over the inner and outer surfaces of a spherical shell formed by two concentric spheres with origin as the center, and internal and external radii of 1 and 2, respectively, is

Solution:



By divergence theorem

*Answer can only contain numeric values
QUESTION: 37

Two business owners Shveta and Ashok run their businesses in two different states. Each of them, independent of the other, produces two products A and B, sells them at Rs. 2,000 per kg and Rs, 3,000 per kg, respectively, and uses Linear Programming to determine the optimal quantity of A and B to maximize their respective daily revenue.
Their constraints are as follows:
i) for each business owner, the production process is such that the daily production of A has to be at least as much as B, and the upper limit for production of B is 10 kg per day, and
ii) the respective state regulations restrict Shveta’s production of A to less than 20 kg per day and Ashok's production of A to less than 15 kg per day. The demand of both A and B in both the states is very high and everything produced is sold.
The absolute value of the difference in daily (optimal) revenue of Shveta and Ashok is ________ thousand Rupees (round off to 2 decimal places)


Solution:

Maximum z = 2000x1 + 3000 x2
A → x1 units
x1 ≥ x2
B → x2 units
x2 ≥ 10
x1 < 20
x1 < 15
Shveta’s Profit = Rs. 70000 at (20, 10)
Ashok’s Profit = Rs. 60000 at (15, 10)
Difference Rs. 10000

*Answer can only contain numeric values
QUESTION: 38

In a disc-type axial clutch, the frictional contact takes place within an annular region with outer and inner diameters 250 mm and 50 mm, respectively. An axial force F1 is needed to transmit a torque by a new clutch. However, to transmit the same torque, one needs an axial force F2 when the clutch wears out. If contact pressure remains uniform during operation of a new clutch while the wear is assumed to be uniform for an old clutch and the coefficient of friction does not change, then the ratio F1/F2  is_________ (round off to 2 decimal places).


Solution:

T = μW × Rm
Tnew = μ × W × Rnew
Tnew
Told = μ × W × Rold
Tnew = Told

= 0.871

*Answer can only contain numeric values
QUESTION: 39

In a turning process using orthogonal tool geometry, a chip length of 100 mm is obtained for an uncut chip length of 250 mm.
The cutting conditions are cutting speed = 30 m/min. rake angle = 20°.
The shear plane angle is _________ degrees (round off to one decimal place).


Solution:



φ = tan–1 (0.4354) = 23.5°

*Answer can only contain numeric values
QUESTION: 40

The magnitude of reaction force at joint C of the hinge-beam shown in the figure is _______ kN (round off to 2 decimal places).


Solution:


ΣMB Right =0
4RC = 10 × 4 × 2
RC = 20 kN

QUESTION: 41

A rigid mass-less rod of length L is connected to a disc (pulley) of mass m and radius r = L/4 through a friction-less revolute joint. The other end of that rod is attached to a wall through a friction-less hinge. A spring of stiffness 2k is attached to the rod at its mid-span. An inextensible rope passes over half the disc periphery and is securely tied to a spring of stiffness k at point C as shown in the figure. There is no slip between the rope and the pulley. The system is in static equilibrium in the configuration shown in the figure and the rope is always taut.

Neglecting the influence of gravity, the natural frequency of the system for small amplitude vibration is

Solution:


MI about point O:

MI about disc centre:
Idisc = mr2/2
When rod rotates by β,
β ⋅ r = l ⋅ θ
β = l ⋅ θ/r
(If disc is also rotating about its own centre due to static friction).
Energy Method:
E = (Rotational KE)system about O + (Rotational KE)disc about its own centre + (PE of spring of 2K) + (PE of spring of K)
E = 

E = 

dE/dt = 0
= 0
 =0
=0
=0
ωnThis is exact solution.
But this solution is very close to 
Because, 

Therefore,
Note: If we take an approximation in moment of inertia about hinge axis.
That, (r = l/4)

If we neglect ml2/32 because ml2/32 <<<< ml2
If we take, I = ml2 
Then we get,
ωn
But if we take exact inertia,

Then exact answer is ωn .

*Answer can only contain numeric values
QUESTION: 42

Air discharges steadily through a horizontal nozzle and impinges on a stationay vertical plate as shown in figure.

The inlet and outlet areas of the nozzle are 0.1 m2 and 0.02 m2, respectively. Take air density as constant and equal to 1.2 kg/m3. If the inlet gauge pressure of air is 0.36 kPa, the gauge pressure at point O on the plate is ________ kPa (round off to two decimal places).


Solution:

On applying continuity equation,
 = ρ1⋅ A1 ⋅v1 = ρ2 ⋅ A2 ⋅ v2
⇒ 0.1V1 =0.02V2
⇒ V2 = 
Now on applying Bernoulli between 1 and 2 section


⇒ 
⇒ V1 = 4.98 m/s
⇒ V2 = 24.89 m/s
On applying Bernoulli between 2 and 3 sections


= 0.375 kPa (gauge)

*Answer can only contain numeric values
QUESTION: 43

For an ideal Rankine cycle operating between pressures of 30 bar and 0.04 bar, the work output from the turbine is 903 kJ/kg and the work input to the feed pump is 3 kJ/kg.
The specific steam consumption is _________________ kg/kW.h (round off to 2 decimal places).


Solution:

WD)turbine = 903 kJ/kg
(WD)pump = 3 kJ/kg
Specific steam consumption = ? (kg/kW-hr)
SSC = 

QUESTION: 44

For an assembly line, the production rate was 4 pieces per hour and the average processing time was 60 minutes. The WIP inventory was calculated. Now, the production rate is kept the same, and the average processing time is brought down by 30 percent.As a result of this change in the processing time, the WIP inventory

Solution:
QUESTION: 45

The truss shown in the figure has four members of length l and flexural rigidity EI, and one member of length l√2 and flexural rigidity 4EI. The truss is loaded by a pair of forces of magnitude P, as shown in the figure.

The smallest value of P, at which any of the truss members will buckle is

Solution:


*Answer can only contain numeric values
QUESTION: 46

A steel part with surface area of 125 cm2 is to be chrome coaled through an electroplating process using chromium acid sulphate as an electrolyte. An increasing current is applied to the part according to the following current time relation:
I = 12 + 0.2t
where, I = current (A) and t = time (minutes). The part is submerged in the plating solution for a duration of 20 minutes for plating purpose. Assuming the cathode efficiency of chromium to be 15% and the plating constant of chromium acid sulphate to be 2.50 × 10–2 mm3/A·s, the resulting coating thickness on the part surface is _________ μm (round off to one decimal place).


Solution:

I = 12 + 0.2t
After time, ‘t’, Next infinitly small time ‘dt’ let heat deposited ‘dQ’.
∴ dQ = 2.50 × 10–2 (mm3/A.s) × 12 + 0.2t × dt As we have to convert this ‘s’ to ‘min’
∴ dQ = 2.50 × 10–2 (mm3/A × min) × 12 + 0.2t × dt
Considering cathode efficiency of 15%
dQ = 2.50 × 10–2 × 60 × (12 + 0.2t )dt × 0.15 mm3
∴ In 20 min,
= 63 mm3
As area os 125 cm2
Plating thickness, t = = 5.04 μm
(As 1 cm2 = 100 mm2)

*Answer can only contain numeric values
QUESTION: 47

An analytic function of a complex variable z = x+iy (i = √-1) is defined as
f (z)= x2 − y2+i ψ ( x,y)
where ψ(x, y) is a real function. The value of the imaginary part of f(z) at z = (1 + i) is ___________ (round off to 2 decimal places).


Solution:

f (z)= φ + i ψ is analytic
φ = x2 – y2

φx =2x = ψy    φy = –ψx
φy =–2y = –ψx
ψx =2y ⇒ ψ = 2xy + C1
ψy =2x ⇒ ψ = 2xy + C2
Comparing ψ =2 xy + C
valid for all C put C = 0
ψ (1 + i) ⇒ (x = 1 y = 1)
∴ ψ =2

QUESTION: 48

A strip of thickness 40 mm is to be rolled to a thickness of 20 mm using a two-high mill having rolls of diameter 200 mm. Coefficient of friction and arc length in mm, respectively are

Solution:

h0 = 40 mm, hf = 20 mm, Δh = 40 – 20 = 20 mm, D = 200 mm, R = 100 mm Projected length,
L = 
Δh = μ2R
∴ 20 = μ2⋅100
∴ 0.2 = μ2
μ = 0.4472

*Answer can only contain numeric values
QUESTION: 49

The barrier shown between two water tanks of unit width (1 m) into the plane of the screen is modeled as a cantilever.

Taking the density of water as 1000 kg/m3, and the acceleration due to gravity as 10 m/s2, the maximum absolute bending moment developed in the cantilever is ______ kNm (round off to the nearest integer).


Solution:


F1
= 1000 × 10 × (1 × 4) × 2 = 80 kN
F2 =  
= 1000 × 10 × (1 × 1) × 0.5 = 5 kN
CP1
CP2
So, MA = 105 kN-m

*Answer can only contain numeric values
QUESTION: 50

Consider two exponentially distributed random variables X and Y, both having a mean of 0.50. Let Z = X + Y and r be the correlation coefficient between X and Y. If the variance of Z equals 0, then the value of r is ___________ (round off to 2 decimal places).


Solution:

X ~ E (λ1); mean = 
⇒λ1 =2
Variance, x = 
Y ~ E (λ2); Mean = 
⇒λ2 =2
Variance, y =0.25
Given Var (Z) = Var(x) + Var (y) + 2 COV (x, y)
0 = 0.25 + 0.25 + 2 COV (x, y )
COV (x, y)= 
Correlation, 

*Answer can only contain numeric values
QUESTION: 51

The thickness of a steel plate with material strength coefficient of 210 MPa, has to be reduced from 20 mm to 15 mm in a single pass in a two-high rolling mill with a roll radius of 450 mm and rolling velocity of 28 m/min. If the plate has a width of 200 mm and its strain hardening exponent, n is 0.25, the rolling force required for the operation is____________kN (round off to 2 decimal places).
Note: Average Flow Stress = Material Strength Coefficient × 


Solution:

True strain, (∈T)= 

F = 
= 1167259.9 N = 1167.26 kN

*Answer can only contain numeric values
QUESTION: 52

Air (ideal gas) enters a perfectly insulated compressor at a temperature of 310 K. The pressure ratio of the compressor is 6. Specific heat at constant pressure for air is 1005 J/kg.K and ratio of specific heats at constant pressure and constant volume is 1.4. Assume that specific heats of air are constant. If the isentropic efficiency of the compressor is 85 percent, the difference in enthalpies of air between the exit and the inlet of the compressor is ________ kJ/kg (round off to nearest integer).


Solution:


T1 =310 K
rp ηs = 0.85
Cp = 1.005 kJ/kgK
γ = 1.4
∴ 
 
⇒T2 = 517.225 K
Now, 

⇒ 

*Answer can only contain numeric values
QUESTION: 53

Consider two cases as below.
Case 1: A company buys 1000 pieces per year of a certain part from vendor 'X'. The changeover time is 2 hours and the price is Rs. 10 per piece. The holding cost rate per part is 10% per year.
Case 2: For the same part, another vendor 'Y" offers a design where the changeover time is 6 minutes, with a price of Rs. 5 per piece, and a holding cost rate per part of 100% per year. The order size is 800 pieces per year from 'X' and 200 pieces per year from 'Y’.
Assume the cost of downtime as Rs. 200 per hour. The percentage reduction in the annual cost for Case 2, as compared to Case 1 is___________ (round off to 2 decimal places).


Solution:

Given Data : 1000 pieces/year from ‘X’.
Changeover time = 2 hrs.
Cost of downtime = Rs. 200/hour
So, Total cost of downtime
2 × 200 = Rs. 400/downtime
C = Rs. 10/piece
Holding cost, Ch = 10% of Rs. 10
Ch = Rs. 1/unit/year
 So, total cost for Case I :
= Material Cost + Downtime Cost + Inventory Holding Cost

Total cost for case I = Rs. 10,900/-
Case II : Order quantity 800 units from X and 200 units from Y.
For Y : Change overtime = 6 min. = 0.1 hour
Downtime cost = 0.1 × 200 = Rs. 20/-
Unit cost, C = Rs. 5/piece
Holding cost, Ch = 100% of unit cost = Rs. 5/-
So, total cost for case II :
= Cost for ‘X ’ + Cost for ‘Y ’

= 8000 + 800 + 1000 + 520
Total cost for case II = Rs. 10,320/-So, percentage reduction in total cost of case II :

*Answer can only contain numeric values
QUESTION: 54

Consider steady, viscous, fully developed flow of a fluid through a circular pipe of internal diameter D. We know that the velocity profile forms a paraboloid about the pipe centre line, given by: V = – C m/s, where C is a constant. The rate of kinetic energy(in J/s) at the control surface A-B, as shown in the figure, is proportional to Dn. The value of n is________.


Solution:




n= 8

*Answer can only contain numeric values
QUESTION: 55

The following data applies to basic shaft system: tolerance for hole = 0.002 mm, tolerance for shaft = 0.001 mm, allowance = 0.003 mm, basic size = 50 mm The maximum hole size is ______ mm (round off to 3 decimal places).


Solution:

Using diagram method

UL of hole = BS + 0.003 + 0.002 mm = 50.005 mm

QUESTION: 56

The 2 kg block shown in figure (top view) rests on a smooth horizontal surface and is attached to a massless elastic cord that has a stiffness 5 N/m.

The cord hinged at O is initially unstretched and always remains elastic. The block is given a velocity v of 1.5 m/s perpendicular to the cord. The magnitude of velocity in m/s of the block at the instant the cord is stretched by 0.4 m is

Solution:

Energy conservation,

⇒ 2 × 1.52
V0 = 1.360 m/s

QUESTION: 57

Bars of square and circular cross-section with 0.5 m length are made of a material with shear strength of 20 MPa. The square bar cross-section dimension is 4 cm x 4 cm and the cylindrical bar cross-section diameter is 4 cm. The specimens are loaded as shown in the figure.

Which specimen(s) will fail due to the applied load as per maximum shear stress theory?

Solution:






= 16 N/mm2 < 20 MPa


*Answer can only contain numeric values
QUESTION: 58

For a Kaplan (axial flow) turbine, the outlet blade velocity diagram at a section is shown in figure.

The diameter at this section is 3 m. The hub and tip diameters of the blade are 2 m and 4 m, respectively. The water volume flow rate is 100 m3/s. The rotational speed of the turbine is 300 rpm. The blade outlet angle β is _________ degrees (round off to one decimal place).


Solution:

Db = 2 m Q = 100 m3/sec
Do = 4 m N = 300 rpm




VF 2 = CF = 10.61 m/s
tanβ = 
⇒ β = 12.69° ≈ 12.7°

*Answer can only contain numeric values
QUESTION: 59

A slot of 25 mm x 25 mm Is lo be milled in a workpiece of 300 mm length using a side and face milling cutter of diameter 100 mm, width 25 mm and having 20 teeth.
For a depth of cut 5 mm, feed per tooth 0.1 mm, cutting speed 35 m/min and approach and over travel distance of 5 mm each, the time required for milling the slot is_______ minutes (round off to one decimal place).


Solution:

V = πDN
35 = π × 0.100 × N
N = π × 111.408 rpm

= 1.6157 min per pass
For 25 mm cuts min 5 mm depth of cut 5 pass needed.
Total machining time = 8.078 min ≈ 8.1 min

QUESTION: 60

A small metal bead (radius 0.5 mm), initially at 100°C, when placed in a stream of fluid at 20°C, attains a temperature of 28°C in 4.35 seconds. The density and specific heat of the metal are 8500 kg/m3 and 400 J/kgK, respectively. If the bead is considered as lumped system, the convective heat transfer coefficient (in W/m2K) between the metal bead and the fluid stream is

Solution:

r = 0.5 mm; cp = 400 J/kgk; ρ = 8500 kg/m3; t = 4.35 sec
∵ 
∵ 
⇒ 
⇒ h = 299.95 W/m2K

QUESTION: 61

The evaluation of the definite integral by using Simpson’s 1/3rd (one-third) rule with step size h = 0.6 yields

Solution:

step size h = 0.6

Simpson’s 1/3rd rule

= 0.2[0.96 + 1.92+ 0.08] = 0.592

*Answer can only contain numeric values
QUESTION: 62

A cam with a translating flat-face follower is desired to have the follower motion
y (θ) = 4[2πθ – θ2], 0 ≤ θ ≤ 2π
Contact stress considerations dictate that the radius of curvature of the cam profile should not be less than 40 mm anywhere. The minimum permissible base circle radius is _____ mm (round off to one decimal place).


Solution:

Flat face follower
Displacement equation:


= 8 ( π− θ) (For y to be max dy/dθ = 0 ⇒ θ = π
a = dv/dθ = -8
(Rcurvature)Min = R Base + (y + a )min  (y min is 0 at θ = 0, 2π)
40 = R Base + [0 – 8]Min
40 = R Base + [–8]
RBase = 40 – (– 8) = 40 + 8 = 48 mm

*Answer can only contain numeric values
QUESTION: 63

One kg of air, initially at a temperature of 127°C, expands reversibly at a constant pressure until the volume is doubled. If the gas constant of air is 287 J/kg.K, the magnitude of work transfer is __________ kJ (round off to 2 decimal places).


Solution:


m = 1 kg; T1 = 127°C = 400 K
P = C; V2 = 2V1;   R = 0.287 kJ/kgK
W = P1(V2 – V1)
= P1(2V1 – V1)
= P1 ·V1 = mRT1
= 114.8 kJ

*Answer can only contain numeric values
QUESTION: 64

A rectangular steel bar of length 500 mm, width 100 mm, and thickness 15 mm is cantilevered to a 200 mm steel channel using 4 bolts, as shown.

For an external load of 10 kN applied at the tip of the steel bar, the resultant shear load on the bolt at B, is ___________ kN (round off to one decimal place).


Solution:


FA = FB = FC = FD= 14.14 kN
ResB
ResB = 16.005 kN

*Answer can only contain numeric values
QUESTION: 65

The indicated power developed by an engine with compression ratio of 8, is calculated using an air-standard Otto cycle {constant properties). The rate of heat addition is 10 kW. The ratio of specific heats at constant pressure and constant volume is 1.4.
The mechanical efficiency of the engine is 80 percent. The brake power output of the engine is ________ kW (round off to one decimal place).


Solution:




BP = ηm × W = 0.8 × 5.647
= 4.5175 kW