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30 Questions MCQ Test - Full Test 1 - EKT Mechanical

Full Test 1 - EKT Mechanical for AFCAT 2024 is part of AFCAT preparation. The Full Test 1 - EKT Mechanical questions and answers have been prepared according to the AFCAT exam syllabus.The Full Test 1 - EKT Mechanical MCQs are made for AFCAT 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Full Test 1 - EKT Mechanical below.
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Full Test 1 - EKT Mechanical - Question 1

If x = cosθ + jsinθ the value of 

Detailed Solution for Full Test 1 - EKT Mechanical - Question 1

Full Test 1 - EKT Mechanical - Question 2

Laplace transform of 3 t4 is

Detailed Solution for Full Test 1 - EKT Mechanical - Question 2


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Full Test 1 - EKT Mechanical - Question 3

Detailed Solution for Full Test 1 - EKT Mechanical - Question 3


A = B ⇒ x− 36 = 0 ⇒ x2 = 36 ⇒ x = ±6

Full Test 1 - EKT Mechanical - Question 4

Detailed Solution for Full Test 1 - EKT Mechanical - Question 4

The given integral is of the beta function. Hence it can be written as

Here n = 4, therefore the integral becomes

Full Test 1 - EKT Mechanical - Question 5

A pair of fair dice is thrown, what is the probability of getting a six on both, given atleast one die gets six?

Detailed Solution for Full Test 1 - EKT Mechanical - Question 5

A = {getting a six a atleast 1}= 1-{getting no six}

B = {getting a six on both}

Probability of getting a six on both, given atleast one die gets six i.e. Probability of B given A

Also A∩B = B


= 1/11

Full Test 1 - EKT Mechanical - Question 6

Detailed Solution for Full Test 1 - EKT Mechanical - Question 6

In the limit, we get the indeterminate form i.e. (∞0).
Rewriting the problem:



This implies that the nth root of n approaches 1 as n approaches infinity.

Full Test 1 - EKT Mechanical - Question 7

Which of the following forces have zero value of resultant?

Detailed Solution for Full Test 1 - EKT Mechanical - Question 7

Equilibrium is the status of the body when it is subjected to a system of forces. If the resultant force is equal to zero it implies that the net effect of the system of forces is zero this represents the state of equilibrium.

Full Test 1 - EKT Mechanical - Question 8

Two bulbs when connected in parallel to a source take 100 W each. The total power consumed when they are connected in series with the same source is 

Detailed Solution for Full Test 1 - EKT Mechanical - Question 8

Series Circuits:
I1 = I2 = I
Rt = R1 + R2
V= Vt = V1 + V2

Parallel circuits:
V1 = V= V
Rt = (1/R1) + (1/R2)
It = I1 + I2
Power = VI = I2R = V2/R
Two bulbs when connected in parallel to a source take 100 W each.

When two bulbs are connected in series:
Rt = R1 + R= 2R

Full Test 1 - EKT Mechanical - Question 9

What is the unit of conductance

Detailed Solution for Full Test 1 - EKT Mechanical - Question 9
  • The degree to which an object conducts electricity is known as conductance
  • It is calculated as the ratio of the current which flows to the potential difference present
  • This is the reciprocal of the resistance and is measured in Siemens or mhos
  • Resistance is measured in ohms
Full Test 1 - EKT Mechanical - Question 10

The capacitance between two long parallel conducting wires depends upon

Detailed Solution for Full Test 1 - EKT Mechanical - Question 10

The capacitance of parallel conducting wires:

Where R is the radius of the wire and d is the distance between conductors

Full Test 1 - EKT Mechanical - Question 11

The speed of electromagnetic waves in free space is _____ m/s.

Detailed Solution for Full Test 1 - EKT Mechanical - Question 11

The speed of electromagnetic waves in free space is equal to the velocity of light.

Full Test 1 - EKT Mechanical - Question 12

The rivet is made of

Detailed Solution for Full Test 1 - EKT Mechanical - Question 12

The material of the rivets must be tough and ductile. They are usually made of steel (low carbon steel or nickel steel), brass, aluminium or copper, but when strength and a fluid tight joint is the main consideration, then the steel rivets are used.

Full Test 1 - EKT Mechanical - Question 13

A key that has curved bottom to match the shaft. This key is known as________

Detailed Solution for Full Test 1 - EKT Mechanical - Question 13

The sunk keys are provided half in the keyway of the shaft and half in the keyway of the hub or boss of the pulley.

A key attached to one member of a pair and which permits relative axial movement is known as feather key. It is a special type of parallel key which transmits a turning moment and permits axial movement.

flat saddle key is a taper key which fits in a keyway in the hub and is flat on the shaft. It is likely to slip round the shaft under load. Therefore, it is used for comparatively light loads.

hollow saddle key is a taper key which fits in a keyway in the hub and the bottom of the key is shaped to fit the curved surface of the shaft. Since hollow saddle keys hold on by friction, therefore these are suitable for light loads. It is usually used as a temporary fastening in fixing and setting eccentrics, cams etc.

Full Test 1 - EKT Mechanical - Question 14

If the load on a ball bearing is reduced to half, the life of the ball bearing will

Detailed Solution for Full Test 1 - EKT Mechanical - Question 14

For ball bearing:
LP3 = C
L1P13 = L2P23
L= 8L1

Full Test 1 - EKT Mechanical - Question 15

When the frictional force helps the applied force in applying the brake, the brake is

Detailed Solution for Full Test 1 - EKT Mechanical - Question 15

When the frictional force helps  the applied force in applying the brake, such type of brakes are said to be self energizing brakes.

When the frictional force is great enough to apply the brake with no external force, then the brake is said to be self-locking brake.
The brake should be self-energizing and not the self-locking.

Full Test 1 - EKT Mechanical - Question 16

How can shock absorbing capacity of a bolt be increased

Detailed Solution for Full Test 1 - EKT Mechanical - Question 16

If the shank of the bolt is turned down to a diameter equal to even slightly less than the core diameter of the thread, then the shank of the bolt will undergo a higher stress. This means that the shank will absorb a large portion of the energy thus relieving the material at the section near the thread. The bolt in this way becomes stronger and lighter and it increase the shock absorbing capacity of the bolt.

Full Test 1 - EKT Mechanical - Question 17

A particle while sliding down a smooth plane of 19.86 √2 m length acquires a velocity of 19.86 m/sec. The inclination of plane is:-

Detailed Solution for Full Test 1 - EKT Mechanical - Question 17


v2 = u2 + 2as

7.021 = 9.8 × sin θ
sin θ = 0.716
θ = 45.76°

Full Test 1 - EKT Mechanical - Question 18

Which of the following are vector quantities?

Detailed Solution for Full Test 1 - EKT Mechanical - Question 18

Vector is a quantity that has both magnitude and direction. In contrast to vectors, ordinary quantities that have a magnitude but not a direction are called scalars. For example, displacement, velocity, and acceleration are vector quantities, while speed (the magnitude of velocity), time, and mass are scalars.

Full Test 1 - EKT Mechanical - Question 19

If the moment on a beam is increased three times, then to keep the stress in the beam same, the sectional modulus should be:

Detailed Solution for Full Test 1 - EKT Mechanical - Question 19



Or simply we can say that for same stress, M∝Z
If M increased to three times, then Z should increase to three times.

Full Test 1 - EKT Mechanical - Question 20

A polar moment of Inertia (I) for hollow shaft with external diameter (D) and internal diameter (d) is given by:

Detailed Solution for Full Test 1 - EKT Mechanical - Question 20

Polar moment of inertia of hollow shaft 

Full Test 1 - EKT Mechanical - Question 21

A cantilever carries a concentrated load (W) at its free end. It's Shear force diagram will be:

Detailed Solution for Full Test 1 - EKT Mechanical - Question 21

RA = w

Vx = RA = w
VA = w, VB = w
Hence, S.F.D. is as shown in figure below

Full Test 1 - EKT Mechanical - Question 22

If the Euler load for a column is 1000 kN and crushing load is 1200 kN, then the Rankine load will approximately be:

Detailed Solution for Full Test 1 - EKT Mechanical - Question 22

Full Test 1 - EKT Mechanical - Question 23

In which one of the following situations the entropy change will be negative.

Detailed Solution for Full Test 1 - EKT Mechanical - Question 23

In case of constant volume the entropy change is given as

Full Test 1 - EKT Mechanical - Question 24

In a reversible heat engine the temperature limits are 100 k and 400 K. If heat output is 200 kJ and heat input is

Detailed Solution for Full Test 1 - EKT Mechanical - Question 24

For a reversible heat engine,


Full Test 1 - EKT Mechanical - Question 25

Gibb’s free energy functions is a property comprises.

Detailed Solution for Full Test 1 - EKT Mechanical - Question 25

Gibb’s free energy function (G)
G = H – TS
G = f(H, T, S)

Full Test 1 - EKT Mechanical - Question 26

Heat transfer takes place according to

Detailed Solution for Full Test 1 - EKT Mechanical - Question 26

Heat transfer takes place according to second law of thermodynamics. Second law of thermodynamics states that “heat will flow naturally from one reservoir to another at a lower temperature, but not in opposite direction without assistance”.

Full Test 1 - EKT Mechanical - Question 27

What is the ratio of thermal conductivity to electrical conductivity equal to?

Detailed Solution for Full Test 1 - EKT Mechanical - Question 27


Note:
The Prandtl number, Pr, is the ratio of the momentum diffusivity (kinematic viscosity) to the thermal diffusivity.

The Reynolds number (Re) is the ratio of inertia forces in the fluid to the viscous forces.

Schmidt and Sherwood numbers are the mass transfer coefficient.
Schmidt number (Sc): Ratio of molecular diffusivity of momentum to molecular diffusivity of mass transfer.

Sherwood number (Sh): Ratio of total mass transfer rate to mass transfer by molecular diffusion

Lewis Number represent the relative magnitudes of heat and mass diffusion in the thermal and concentration boundary layers.

Lorenz Number: Wiedemann–Franz law states that the ratio of the electrical to the thermal conductivity was a constant for several metals, at a given temperature.

Full Test 1 - EKT Mechanical - Question 28

An impulse hydraulic turbine:

Detailed Solution for Full Test 1 - EKT Mechanical - Question 28

Impulse turbine: At the inlet of the turbine, the energy available is only kinetic energy

Example: Pelton Turbine

Reaction Turbine: At the inlet of the turbine, the water possesses kinetic energy as well as pressure energy

Example: Francis Turbine, Kaplan Turbine

Full Test 1 - EKT Mechanical - Question 29

The specific gravity of liquids is usually measured by means of a:

Detailed Solution for Full Test 1 - EKT Mechanical - Question 29

A hydrometer or areometer is an instrument that measures the specific gravity (relative density) of liquids-the ratio of the density of the liquid to the density of water.

A hygrometer, also known as a psychrometer, is a device that is used to measure the humidity in the air.

A thermometer is a device that measures temperature or a temperature gradient.

A piezometer is a device used to measure liquid pressure in a system by measuring the height to which a column of the liquid rises against gravity.

Full Test 1 - EKT Mechanical - Question 30

The cavitation in a hydraulic machine ________.

Detailed Solution for Full Test 1 - EKT Mechanical - Question 30

Cavitation is defined as the phenomenon of formation of vapour bubbles of a flowing liquid in a region where the pressure of the liquid falls below its vapour pressure and the sudden collapsing of these vapour bubbles in a region of higher pressure. When the vapour pressure collapse, very high pressure is created.

Effects of cavitation:

(i) The metallic surfaces are damaged and cavities are formed on the surfaces.

(ii) Due to the sudden collapse of the vapour bubble, considerable noise and vibrations are produced.

(iii) Due to cavitation, the metal of the runner vanes and the draft tube is gradually eaten away, which results in lowering the efficiency of the turbine.

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