Question text and figures as in the official paper, with the answer from the official key. Worked solutions for every question are in your report after you take the paper as a 3-hour test.
Writing too many things on the ________ while teaching could make the students get _________.
(A)
bored / board
(B)
board / bored
(C)
board / board
(D)
bored / bored
Answer (official key): B
Worked solution: in your report after you take this paper.
Q2 · General Aptitude · MCQ · 1 mark
Which one of the following is a representation (not to scale and in bold) of all values of x satisfying the inequality 2−5x≤−36x−5 on the real number line?
(A)
(B)
(C)
(D)
Answer (official key): C
Worked solution: in your report after you take this paper.
Q3 · General Aptitude · MCQ · 1 mark
If f(x)=2ln(ex), what is the area bounded by f(x) for the interval [0,2] on the x-axis?
(A)
21
(B)
1
(C)
2
(D)
4
Answer (official key): C
Worked solution: in your report after you take this paper.
Q4 · General Aptitude · MCQ · 1 mark
A person was born on the fifth Monday of February in a particular year.
Which one of the following statements is correct based on the above information?
(A)
The 2nd February of that year is a Tuesday
(B)
There will be five Sundays in the month of February in that year
(C)
The 1st February of that year is a Sunday
(D)
All Mondays of February in that year have even dates
Answer (official key): A
Worked solution: in your report after you take this paper.
Q5 · General Aptitude · MCQ · 1 mark
Which one of the groups given below can be assembled to get the shape that is shown above using each piece only once without overlapping with each other? (rotation and translation operations may be used).
Fish belonging to species S in the deep sea have skins that are extremely black (ultra-black skin). This helps them not only to avoid predators but also sneakily attack their prey. However, having this extra layer of black pigment results in lower collagen on their skin, making their skin more fragile.
Which one of the following is the CORRECT logical inference based on the information in the above passage?
(A)
Having ultra-black skin is only advantageous to species S
(B)
Species S with lower collagen in their skin are at an advantage because it helps them avoid predators
(C)
Having ultra-black skin has both advantages and disadvantages to species S
(D)
Having ultra-black skin is only disadvantageous to species S but advantageous only to their predators
Answer (official key): C
Worked solution: in your report after you take this paper.
Q7 · General Aptitude · MCQ · 2 marks
For the past m days, the average daily production at a company was 100 units per day.
If today’s production of 180 units changes the average to 110 units per day, what is the value of m?
(A)
18
(B)
10
(C)
7
(D)
5
Answer (official key): C
Worked solution: in your report after you take this paper.
Q8 · General Aptitude · MCQ · 2 marks
Consider the following functions for non-zero positive integers, p and q.
f(p,q)=q termsp×p×p×⋯×p=pq;f(p,1)=p
g(p,q)=pppp⋅⋅⋅(up to q terms);g(p,1)=p
Which one of the following options is correct based on the above?
(A)
f(2,2)=g(2,2)
(B)
f(g(2,2),2)<f(2,g(2,2))
(C)
g(2,1)=f(2,1)
(D)
f(3,2)>g(3,2)
Answer (official key): A
Worked solution: in your report after you take this paper.
Q9 · General Aptitude · MCQ · 2 marks
Four cities P, Q, R and S are connected through one-way routes as shown in the figure. The travel time between any two connected cities is one hour. The boxes beside each city name describe the starting time of first train of the day and their frequency of operation. For example, from city P, the first trains of the day start at 8 AM with a frequency of 90 minutes to each of R and S. A person does not spend additional time at any city other than the waiting time for the next connecting train.
If the person starts from R at 7 AM and is required to visit S and return to R, what is the minimum time required?
Equal sized circular regions are shaded in a square sheet of paper of 1 cm side length. Two cases, case M and case N, are considered as shown in the figures below. In the case M, four circles are shaded in the square sheet and in the case N, nine circles are shaded in the square sheet as shown.
What is the ratio of the areas of unshaded regions of case M to that of case N?
(A)
2 : 3
(B)
1 : 1
(C)
3 : 2
(D)
2 : 1
Answer (official key): B
Worked solution: in your report after you take this paper.
Q11 · Calculus · MCQ · 1 mark
The equation of the straight line representing the tangent to the curve y=x2 at the point (1,1) is
(A)
y=2x−2
(B)
x=2y−1
(C)
y−1=2(x−1)
(D)
x−1=2(y−1)
Answer (official key): C
Worked solution: in your report after you take this paper.
Q12 · Linear Algebra · MCQ · 1 mark
Let ^,^, and k^ be the unit vectors in the x, y and z directions, respectively. If the vector ^+^ is rotated about positive k^ by 135°, one gets
(A)
−^
(B)
−^
(C)
−21^
(D)
−2^
Answer (official key): D
Worked solution: in your report after you take this paper.
Q13 · Calculus · MCQ · 1 mark
Let x be a real number and i=−1. Then the real part of cos(ix) is
(A)
sinhx
(B)
coshx
(C)
cosx
(D)
sinx
Answer (official key): B
Worked solution: in your report after you take this paper.
Q14 · Aerodynamics · MCQ · 1 mark
The point of maximum entropy on a Fanno-curve in a Temperature-Entropy (T-s) diagram represents the
(A)
maximum flow Mach number
(B)
minimum flow Mach number
(C)
sonic Mach number
(D)
normal shock in the flow
Answer (official key): C
Worked solution: in your report after you take this paper.
Q15 · Aerodynamics · MCQ · 1 mark
Consider a two-dimensional potential flow over a cylinder. If the freestream speed is U∞, the maximum speed on the cylinder surface is
(A)
2U∞
(B)
23U∞
(C)
2U∞
(D)
34U∞
Answer (official key): C
Worked solution: in your report after you take this paper.
Q16 · Aerodynamics · MCQ · 1 mark
Consider steady, two-dimensional, incompressible flow over a non-porous flat plate as shown in the figure. For the control volume PQRS, the speed, u∞, at section PQ is uniform and the speed at section RS is given by u(y)=A0(hy)n, where n is a positive integer. The value of A0 for which the flow through section PS will vanish is:
(A)
n+1u∞
(B)
u∞(n+1)
(C)
n−1u∞
(D)
u∞(n−1)
Answer (official key): B
Worked solution: in your report after you take this paper.
Q17 · Aerodynamics · MCQ · 1 mark
Consider the velocity distribution, u(y) shown in the figure. For two adjacent fluid layers L1 and L2, the viscous force exerted by L1 on L2 is
(A)
to the right
(B)
to the left
(C)
vertically upwards
(D)
vertically downwards
Answer (official key): B
Worked solution: in your report after you take this paper.
Q18 · Flight Mechanics · MCQ · 1 mark
The service ceiling of an airplane is the altitude
(A)
at which maximum rate of climb is 100 m/min
(B)
beyond which theoretically the airplane cannot sustain level flight
(C)
at which maximum power is required for flight
(D)
at which maximum rate of climb is 100 ft/min
Answer (official key): D
Worked solution: in your report after you take this paper.
Q19 · Flight Mechanics · MCQ · 1 mark
Regarding the horizontal tail of a conventional airplane, which one of the following statements is true?
(A)
It contributes to Cmα<0
(B)
It makes Cmα=0
(C)
It makes Cmα>0
(D)
It makes Cm0>0 and Cmα>0
Answer (official key): A
Worked solution: in your report after you take this paper.
Q20 · Structures · MCQ · 1 mark
A beam with a symmetrical T-shaped cross-section, as shown in the figure, is subjected to pure bending. The maximum magnitude of the normal stress is realised:
(A)
only at the top fibres of the cross-section
(B)
only at the bottom fibres of the cross-section
(C)
both at the top and bottom fibres of the cross-section
(D)
only at the centroidal fibres of the cross-section
Answer (official key): B
Worked solution: in your report after you take this paper.
Q21 · Structures · MCQ · 1 mark
A three-member truss is simply supported at Q and R, and loaded at P by a horizontal force F as shown. The force in QR is
(A)
0
(B)
F (tensile)
(C)
2F (compressive)
(D)
2F (tensile)
Answer (official key): B
Worked solution: in your report after you take this paper.
Q22 · Structures · MCQ · 1 mark
The closed thin-walled rectangular channel shown in figure (i) is opened by introducing a sharp cut at the center of the bottom edge, as shown in figure (ii). Which one of the following statements is correct?
(A)
Centroids of (i) and (ii) coincide while shear centers do not
(B)
Shear centers of (i) and (ii) coincide while centroids do not
(C)
Both centroids and shear centers of (i) and (ii) coincide
(D)
Neither centroids nor shear centers of (i) and (ii) coincide
Answer (official key): A
Worked solution: in your report after you take this paper.
Q23 · Propulsion · MCQ · 1 mark
The region of highest static temperature in a rocket engine and the region of highest heat flux are ____________, respectively.
(A)
nozzle throat and nozzle entry
(B)
combustion chamber and nozzle throat
(C)
nozzle exit and nozzle throat
(D)
nozzle throat and combustion chamber
Answer (official key): B
Worked solution: in your report after you take this paper.
Q24 · Calculus · MSQ · 1 mark
If a^,b^,c^ are three mutually perpendicular unit vectors, then a^⋅(b^×c^) can take the value(s)
(A)
0
(B)
1
(C)
-1
(D)
∞
Answer (official key): B, C
Worked solution: in your report after you take this paper.
Q25 · Aerodynamics · MSQ · 1 mark
Across an oblique shock wave in a calorifically perfect gas,
(A)
the stagnation enthalpy changes
(B)
the stagnation entropy changes
(C)
the stagnation temperature changes
(D)
the speed of sound changes
Answer (official key): B, D
Worked solution: in your report after you take this paper.
Q26 · Aerodynamics · MSQ · 1 mark
NACA 2412 airfoil has
(A)
4% maximum camber with respect to chord
(B)
maximum camber at 40% chord
(C)
12% maximum thickness to chord ratio
(D)
maximum camber at 20% chord
Answer (official key): B, C
Worked solution: in your report after you take this paper.
Q27 · Flight Mechanics · MSQ · 1 mark
For International Standard Atmosphere (ISA) up to 11 km, which of the following statement(s) is/are true?
(A)
The hydrostatic/ aerostatic equation is used
(B)
The temperature lapse rate is taken as −10−2K/m
(C)
The sea level conditions are taken as: pressure, ps=1.01325×105Pa; temperature, Ts=300K; density, ρs=1.225kg/m3
(D)
Air is treated as a perfect gas
Answer (official key): A, D
Worked solution: in your report after you take this paper.
Q28 · Structures · MSQ · 1 mark
Let σ and τ represent the normal stress and shear stress on a plane, respectively. The Mohr circle(s) that may possibly represent the state of stress at points in a beam of rectangular cross-section under pure bending is/are:
(A)
(B)
(C)
(D)
Answer (official key): B, C
Worked solution: in your report after you take this paper.
Q29 · Structures · MSQ · 1 mark
An isotropic linear elastic material point under plane strain condition in the x-y plane always obeys:
(A)
out-of-plane normal strain, ϵzz=0
(B)
out-of-plane normal stress, σzz=0
(C)
out-of-plane shear stress, τxz=0
(D)
out-of-plane shear strain, γxz=0
Answer (official key): A, C, D
Worked solution: in your report after you take this paper.
Q30 · Propulsion · MSQ · 1 mark
A high-pressure-ratio multistage axial compressor encounters an extreme loading mismatch during starting. Which of the following technique(s) can be used to alleviate this problem?
(A)
Blade cooling
(B)
Variable angle stator vanes
(C)
Blow-off valves
(D)
Multi-spool shaft
Answer (official key): B, C, D
Worked solution: in your report after you take this paper.
Q31 · Calculus · Numerical · 1 mark
The arc length of the parametric curve: x=cosθ, y=sinθ, z=θ from θ=0 to θ=2π is equal to ________ (round off to one decimal place).
Answer (official key): 8.6 to 9.1
Worked solution: in your report after you take this paper.
Q32 · Flight Mechanics · Numerical · 1 mark
An unpowered glider is flying at a glide angle of 10 degrees. Its lift-to-drag ratio is ______________ (round off to two decimal places).
Answer (official key): 5.55 to 5.8
Worked solution: in your report after you take this paper.
Q33 · Structures · Numerical · 1 mark
The two-dimensional plane-stress state at a point is:
σxx=110MPa;σyy=30MPa;τxy=40MPa.
The normal stress, σn, on a plane inclined 45° as shown in the figure is ____ MPa (round off to the nearest integer).
Answer (official key): 109 to 111
Worked solution: in your report after you take this paper.
Q34 · Propulsion · Numerical · 1 mark
In a static test, a turbofan engine with bypass ratio of 9 has core hot exhaust speed 1.5 times that of fan exhaust speed. The engine is operated at a fuel to air ratio of f=0.03. Both the fan and the core streams have no pressure thrust. The ratio of fan thrust to thrust from the core engine is _____ (round off to one decimal place).
Answer (official key): 5.7 to 6
Worked solution: in your report after you take this paper.
Q35 · Propulsion · Numerical · 1 mark
In a single stage turbine, the hot gases come out of stator/ nozzle at a speed of 500 m/s and at an angle of 70 degrees with the turbine axis as shown. The design speed of the rotor blade is 250 m/s at the mean blade radius. The rotor blade angle, β, at the leading edge is ________ degrees (round off to one decimal place).
Answer (official key): 51.5 to 52.6
Worked solution: in your report after you take this paper.
Q36 · Calculus · MCQ · 2 marks
The height of a right circular cone of maximum volume that can be enclosed within a hollow sphere of radius R is
(A)
R
(B)
45R
(C)
34R
(D)
23R
Answer (official key): C
Worked solution: in your report after you take this paper.
Q37 · Differential Equations · MCQ · 2 marks
Consider the differential equation dx2d2y−2dxdy+y=0.
The boundary conditions are y=0 and dxdy=1 at x=0.
Then the value of y at x=1/2 is
(A)
0
(B)
e
(C)
2e
(D)
2e
Answer (official key): C
Worked solution: in your report after you take this paper.
Q38 · Differential Equations · MCQ · 2 marks
Consider the partial differential equation ∂x2∂2f+∂y2∂2f=0 where x,y are real.
If f(x,y)=a(x)b(y), where a(x) and b(y) are real functions, which one of the following statements can be true?
(A)
a(x) is a periodic function and b(y) is a linear function
(B)
both a(x) and b(y) are exponential functions
(C)
a(x) is a periodic function and b(y) is an exponential function
(D)
both a(x) and b(y) are periodic functions
Answer (official key): C
Worked solution: in your report after you take this paper.
Q39 · Aerodynamics · MCQ · 2 marks
A cylindrical object of diameter 900 mm is designed to move axially in air at 60 m/s. Its drag is estimated on a geometrically half-scaled model in water, assuming flow similarity.
Coefficients of dynamic viscosity and densities for air and water are 1.86×10−5 Pa-s, 1.2 kg/m³ and 1.01×10−3 Pa-s, 1000 kg/m³ respectively.
Drag measured for the model is 2280 N. Drag experienced by the full-scale object is ____ N (rounded off to the nearest integer).
(A)
322
(B)
644
(C)
1288
(D)
2576
Answer (official key): B
Worked solution: in your report after you take this paper.
Q40 · Flight Mechanics · MCQ · 2 marks
Consider a conventional subsonic fixed-wing airplane. e is the Oswald efficiency factor and AR is the aspect ratio. Corresponding to the minimum (CL3/2CD), which of the following relations is true?
(A)
CL2CD=πeAR1
(B)
CL2CD=3πeAR4
(C)
CLCD=πeAR1
(D)
CLCD=πeAR1
Answer (official key): B
Worked solution: in your report after you take this paper.
Q41 · Structures · MCQ · 2 marks
A horizontal load F is applied at point R on a two-member truss, as shown in the figure. Both the members are prismatic with cross-sectional area, A0, and made of the same material with Young’s modulus E.
The horizontal displacement of point R is:
(A)
0
(B)
EA0Fl
(C)
2EA0Fl
(D)
2EA0Fl
Answer (official key): C
Worked solution: in your report after you take this paper.
Q42 · Propulsion · MCQ · 2 marks
Which of the following is NOT always true for a combustion process taking place in a closed system?
(A)
Total number of atoms is conserved
(B)
Total number of molecules is conserved
(C)
Total number of atoms of each element is conserved
(D)
Total mass is conserved
Answer (official key): B
Worked solution: in your report after you take this paper.
Q43 · Calculus · MSQ · 2 marks
The real function y=sin2(∣x∣) is
(A)
continuous for all x
(B)
differentiable for all x
(C)
not continuous at x=0
(D)
not differentiable at x=0
Answer (official key): A, B
Worked solution: in your report after you take this paper.
Q44 · Aerodynamics · MSQ · 2 marks
A convergent nozzle fed from a constant pressure, constant temperature reservoir, is discharging air to atmosphere at 1 bar (absolute) with choked flow at the exit (marked as Q).
Flow through the nozzle can be assumed to be isentropic.
If the exit area of the nozzle is increased while all the reservoir parameters and ambient conditions remain the same, then at steady state
(A)
the nozzle will remain choked
(B)
the nozzle will be un-choked
(C)
the Mach number at section P will increase
(D)
the Mach number at section P will decrease
Answer (official key): A, C
Worked solution: in your report after you take this paper.
Q45 · Flight Mechanics · MSQ · 2 marks
For a conventional airplane in straight, level, constant velocity flight condition, which of the following condition(s) is/are possible on Euler angles (ϕ,θ,ψ), angle of attack (α) and the sideslip angle (β)?
Consider a high Earth-orbiting satellite of angular momentum per unit mass h and eccentricity e.
The mass of the Earth is M and G is the universal gravitational constant.
The distance between the satellite’s center of mass and the Earth’s center of mass is r, the true anomaly is θ, and the phase angle is zero.
Which of the following statements is/are true?
(A)
The trajectory equation is r=r(θ)=GM(1+ecosθ)∣h∣
(B)
The trajectory equation is r=r(θ)=GM(1+ecosθ)∣h∣2
(C)
h is conserved
(D)
The sum of potential energy and kinetic energy of the satellite is conserved
Answer (official key): B, C, D
Worked solution: in your report after you take this paper.
Q47 · Propulsion · MSQ · 2 marks
A rocket operates at an absolute chamber pressure of 20 bar to produce thrust, F1.
The hot exhaust is optimally expanded to 1 bar (absolute pressure) using a convergent-divergent nozzle with exit to throat area ratio (AtAe) of 3.5 and thrust coefficient, CF,1 = 1.42.
The same rocket when operated at an absolute chamber pressure of 50 bar produces thrust F2 and the thrust coefficient is CF,2.
Which of the following statement(s) is/are correct?
(A)
F1F2=2.5
(B)
F1F2>2.5
(C)
CF,1CF,2=1
(D)
CF,1CF,2>1
Answer (official key): B, D
Worked solution: in your report after you take this paper.
Q48 · Calculus · Numerical · 2 marks
v=x3^+y3^+z3k^ is a vector field where ^,^,k^ are the base vectors of a cartesian coordinate system.
Using the Gauss divergence theorem, the value of the outward flux of the vector field over the surface of a sphere of unit radius centered at the origin is________ (rounded off to one decimal place).
Answer (official key): 7.4 to 7.7
Worked solution: in your report after you take this paper.
Q49 · Linear Algebra · Numerical · 2 marks
The largest eigenvalue of the given matrix is _____.
011101110
Answer (official key): 2
Worked solution: in your report after you take this paper.
Q50 · Aerodynamics · Numerical · 2 marks
A rotational velocity field in an air flow is given as V=ayi^+bxj^, with a = 10 s⁻¹, b = 20 s⁻¹.
The air density is 1.0 kg/m³ and the pressure at (x,y) = (0 m, 0 m) is 100 kPa.
Neglecting gravity, the pressure at (x,y) = (6 m, 8 m) is _____ kPa (rounded off to nearest integer).
The wingspan b is 10 m, the maximum circulation Γ0 is 20 m²/s, density of air is 1.2 kg/m³ and the free stream speed is 80 m/s.
The lift over the wing is ______N (rounded off to the nearest integer).
Answer (official key): 9500 to 9800
Worked solution: in your report after you take this paper.
Q52 · Aerodynamics · Numerical · 2 marks
Consider a solid cylinder housed inside another cylinder as shown in the figure. Radius of the inner cylinder is 1 m and its height is 2 m. The gap between the cylinders is 5 mm and is filled with a fluid of viscosity 10⁻⁴ Pa-s.
The inner cylinder is rotating at a constant angular speed of 5 rad/s while the outer cylinder is stationary. Friction at the bottom surfaces can be ignored. Velocity profile in the vertical gap between the cylinders can be assumed to be linear.
The driving moment required for the rotating motion of the inner cylinder is ____________ Nm (rounded off to two decimal places).
Answer (official key): 1.24 to 1.28
Worked solution: in your report after you take this paper.
Q53 · Aerodynamics · Numerical · 2 marks
In a converging duct, area and velocity at section P are 1 m² and 15 m/s, respectively. The temperature of the fluid is 300 K.
Air flow through the nozzle can be assumed to be inviscid and isothermal. Characteristic gas constant is 287 J/(kg-K) and ratio of specific heats is 1.4 for air.
To ensure that the air flow remains incompressible (Mach number, M≤0.3) in the duct, the minimum area required at section Q is _____ m² (rounded off to two decimal places).
Consider a thin symmetric airfoil at 2 degree angle of attack in a uniform flow at 50 m/s. The pitching moment coefficient about its leading edge is _____(rounded off to three decimal places).
Answer (official key): -0.057 to -0.053
Worked solution: in your report after you take this paper.
Q55 · Aerodynamics · Numerical · 2 marks
A convergent-divergent nozzle with adiabatic walls is designed for an exit Mach number of 2.3. It is discharging air to atmosphere under the conditions indicated in the figure.
Flow through the nozzle is inviscid, the characteristic gas constant for air is 287 J/(kg-K), and γ = 1.4.
When the reservoir pressure is 25 bar (absolute), and temperature is 300 K, Prandtl-Meyer expansion waves appear at the nozzle exit as shown.
The minimum percentage change in the reservoir pressure required to eliminate the wave system at the nozzle exit under steady state is _______%.
Answer (official key): 49 to 51 or -51 to -49
Worked solution: in your report after you take this paper.
Q56 · Flight Mechanics · Numerical · 2 marks
A conventional airplane of mass 5000 kg is doing a level turn of radius 1000 m at a constant speed of 100 m/s at sea level.
Taking the acceleration due to gravity as 10 m/s², the bank angle of the airplane is ______________ degrees.
Answer (official key): 44 to 46
Worked solution: in your report after you take this paper.
Q57 · Structures · Numerical · 2 marks
Given: The tip deflection and tip slope for a tip loaded cantilever of length L are: 3EINL3 and 2EINL2, respectively, where N is the tip force and EI is the flexural rigidity.
A cantilever PQ of rectangular cross-section is subjected to transverse load, F, at its mid-point. Two cases are considered as shown in the figure. In Case I, the end Q is free and in Case II, Q is simply supported.
The ratio of the magnitude of the maximum bending stress at P in Case I to that in Case II is ________ (rounded off to one decimal place).
Answer (official key): 2.6 to 2.7
Worked solution: in your report after you take this paper.
Q58 · Structures · Numerical · 2 marks
A simply supported Aluminium column of length 1 m and rectangular cross-section w×t with t≤w, is subjected to axial compressive loading.
Young’s modulus is 70 GPa. Yield stress under uniaxial compression is 120 MPa.
The value of t at which the failure load for yielding and buckling coincide is _______mm.
Answer (official key): 43 to 48
Worked solution: in your report after you take this paper.
Q59 · Structures · Numerical · 2 marks
A 0.5 m long thin-walled circular shaft of radius 2 cm is to be designed for an axial load of 7.4 kN and a torque of 148 Nm applied at its tip, as shown in the figure.
The allowable stress under uniaxial tension is 100 MPa.
Using maximum principal stress criterion, the minimum thickness, t, of the shaft so that it does not fail is _____ mm (rounded off to the nearest integer).
Answer (official key): 1
Worked solution: in your report after you take this paper.
Q60 · Structures · Numerical · 2 marks
A 10 kN axial load is applied eccentrically on a rod of square cross-section (1 cm × 1 cm) as shown in the figure.
The strains measured by the two strain gages attached to the top and bottom surfaces at a distance of 0.5 m from the tip are ϵ1 = 0.0016 and ϵ2 = 0.0004, respectively.
The eccentricity in loading, e is _________mm.
Answer (official key): 0.95 to 1.05
Worked solution: in your report after you take this paper.
Q61 · Structures · Numerical · 2 marks
For a thin-walled I section, the width of the two flanges as well as the web height are the same, i.e., 2b = 20 mm. Thickness is 0.6 mm.
The second moment of area about a horizontal axis passing through the centroid is ______ mm⁴.
Answer (official key): 2700 to 2960
Worked solution: in your report after you take this paper.
Q62 · Structures · Numerical · 2 marks
A damper with damping coefficient, c, is attached to a mass of 5 kg and spring of stiffness 5 kN/m as shown in figure. The system undergoes under-damped oscillations.
If the ratio of the 3rd amplitude to the 4th amplitude of oscillations is 1.5, the value of c is ____ Ns/m (rounded off to the nearest integer).
Answer (official key): 19 to 21
Worked solution: in your report after you take this paper.
Q63 · Structures · Numerical · 2 marks
A uniform rigid prismatic bar of total mass m is suspended from a ceiling by two identical springs as shown in figure. Let ω1 and ω2 be the natural frequencies of mode I and mode II respectively (ω1<ω2).
The value of ω2/ω1 is _________ (rounded off to one decimal place).
Answer (official key): 1.7 to 1.8
Worked solution: in your report after you take this paper.
Q64 · Propulsion · Numerical · 2 marks
An ideal ramjet is to operate with exhaust gases optimally expanded to ambient pressure at an altitude where temperature is 220 K. The exhaust speed at the nozzle exit is 1200 m/s at a temperature of 1100 K.
Given: γ = 1.4 at 220 K; R = 287 J/(kg-K) for air
γ = 1.33 at 1100 K; R = 287 J/(kg-K) for exhaust gases.
The cruise speed of this ramjet is ________ m/s (rounded off to nearest integer).
Answer (official key): 545 to 555
Worked solution: in your report after you take this paper.
Q65 · Propulsion · Numerical · 2 marks
A multistage axial compressor takes in air at 1 atm, 300 K and compresses it to a minimum of 5 atm.
The mean blade speed is 245 m/s and work coefficient, UΔCθ is 0.55 for each stage. For air, use Cp = 1005 J/(kg-K), R = 287 J/(kg-K) and γ = 1.4.
If the compression is isentropic, the number of stages required is ___________ (rounded off to the next higher integer).
Answer (official key): 6 to 1000000
Worked solution: in your report after you take this paper.